Whether you're navigating post-M&A IT complexities, or trying to manage digital sprawl, merging Microsoft 365 tenants is often the solution of choice to tame the chaos. There are, however, potential pitfalls that make merging Microsoft tenants more challenging than most organizations imagine, chief among them the “privilege problem”. That is, consolidation is frequently not possible because putting everyone and everything into a single tenant creates major privilege and access rights challenges. And this is the kind of migration and integration problem that leads to frustration and possibly even failure.
In fact, a Bain report states that 83% of practitioners cite poor integration as one of the primary causes of failed deals. Done right, though, tenant consolidation is not only possible, it also simplifies complexity, boosts security by reducing the potential attack surface, and makes collaboration easier. This article chronicles how to merge Microsoft 365 tenants, the reasons for a possible 365 tenant consolidation, and what steps to consider and take to combine M365 tenants, particularly after a merger or acquisition process.
Inside this article:
Merging Microsoft 365 tenants after a merger or acquisition is a complex, high-stakes process that involves not only technical migration but also business, cultural, and security considerations. The biggest challenges include privilege management, security risks, and aligning IT governance. Successful tenant consolidation requires meticulous pre-migration planning, thorough auditing, strategic user provisioning, and post-migration optimization. CoreView simplifies this process with tools for visibility, virtual tenant segmentation and granular delegation, automation, and compliance. The guide outlines best practices and phased steps—pre-migration, migration, and post-migration—emphasizing that tenant merges are as much about people and processes as technology. CoreView helps mitigate risks while improving productivity and security.
Microsoft 365 tenant consolidation is the process by which the resources of two or more M365 environments are merged into a single, unified tenant. The idea is that the resources of individual tenants, including all users, domains, policies, licenses and configurations, can be moved successfully to a new master tenant.
Merging M365 tenants is a complex but often necessary project involving data mapping and migration, domain management, identity management and consolidation, and data governance alignment, among other processes. Each tenant merge is unique, which is why there is no one-size-fits-all approach to tenant consolidation and migration and why careful planning is essential. CoreView’s Director of Product, Alberto Brianza, explains that a tenant merging process is “not a tech project. It’s about merging, or redefining, business processes between the new unified entity and aligning information flows and IT processes to match it. The organizational and cultural structure of the company has to be reflected by their information systems and enabling and empowering the new organization.”
Organizations merge Microsoft 365 tenants for a variety of reasons, including everything from the most common use case – mergers and acquisitions – to compliance, productivity, or security demands.
At its most basic, a key reason for, or ideal result of, merging tenants is to create an optimal user experience. Microsoft 365 & Azure Subject Matter Expert, Vasil Michev, shares, “In the context of cloud services, you want to end up in a situation where all your objects and users are in the same tenant because this allows for the best end-user experience, for example with being able to easily collaborate or share documents – all much easier within the confines of a single, unified tenant.”
Even if the M365 tenant consolidation process appears to be purely a technical migration, there are always human-centered concerns at play, motivating how M365 tenants are merged. Merging tenants involves not only joining companies’ IT infrastructure and operations but also joining different companies’ cultures together, which inevitably involves people, processes, and politics as well as strategic business decisions that influence the consolidation process, especially in M&A situations.
“Administrative control over a tenant, and all of the related behind-the-scenes mechanisms, is typically quite political and sensitive,” explains CoreView’s Senior Director, Solution Architecture, Simon Hughes. “Certain people in organizations have high levels of privilege within their tenants, and other people rely on those people to do their jobs easily. In any consolidation process, there is the perceived or real risk that the power to manage this change is not reconstituted back into the consolidated tenant correctly. This is a source of political tension. Part of making the case for merging M365 tenants is establishing the right balance of power and ensuring that you have the tooling in place to grant exactly the right level of privilege in the newly combined environment – whatever the reasons for the merger of M365 tenants.”
Consultancy Gartner has added flavor to this tension. Despite the idea that a single tenant offers the optimal experience and a single point of administration, in practice, organizations find that single tenants do not meet the complex requirements for data and user separation, service isolation, and data residency. These sentiments are echoed in an upcoming CoreView survey of 250 IT leaders, in which they cite the pains of multi-tenant management and the inherent challenges of tenant consolidation. Complexity runs through both, with IT leaders citing everything from high operational overhead (55%), excessive licensing costs (47%), and inconsistent configuration (46%) as challenges of multi-tenant management and, on the flip side, unwillingness to consolidate tenants stemming from each tenant having its own operating model (47%) and worries that consolidation will undermine least privilege (35%).
As such, making a tenant consolidation project work demands some way to both consolidate and simplify at the same time as being able to segment and isolate users, group, and devices in ways that enable granular permissions while retaining some of the underlying complexity that multiple tenants afforded.
A big part of a successful tenant consolidation initiative is understanding these complex cultural, political, and productivity issues, and locating the technical solutions and workarounds that can reduce the cultural resistance to M&A processes. As Simon explains, businesses need to make a lot of decisions when consolidating tenants, and this can be tricky. “An organization needs to compare and contrast tenants, and there isn’t adequate native tooling to do this. Determining which of multiple existing tenants is ‘best’, which should be the primary tenant to move everything into, whether a company should start over from scratch with a greenfield tenant project, and then what objects actually need to exist in the new unified tenant are all questions that need to be answered.”
But these organizational and technical decisions are just one challenge. Another, and possibly most significant, challenge is, as Simon describes it, “the power problem”: who has administrative control over a tenant, who believes they need access, and so on? In many cases, organizations have struggled to consolidate tenants for these kinds of reasons. Because they have not historically been able to segment privilege and permissions at a more granular level, companies have had all-or-nothing-style dilemmas. That is, choose between security or productivity; choose restricting access and permissions to the point that productivity suffers and people are unhappy, or open the floodgates and overdeliver access to everything, which might help productivity but exposes the tenant and all its data (and the organization as a whole) to much wider and broader risk.
Every tenant consolidation endeavor is as unique as the resources that live within each tenant, and as such, no blanket blueprint exists for merging M365 tenants. At a high level the process is roughly the same across use cases, with particular aspects being critical across the board. Robust and comprehensive upfront business planning, according to CoreView’s Chief Technology Officer, Ivan Fioravanti, can make or break a tenant merger initiative.
“Visibility is key,” Ivan explains. “Not only do you need a full and precise picture of the technical aspects your tenant merger needs to achieve, you also need to understand the cultural and structural underpinnings of your organization as it relates to business continuity, productivity, and making sure that everyone is able to do their jobs once your merger happens. Fundamentally tenant consolidation comes down to people. When people are unhappy because things don’t work, the organization struggles. But if you can act pre-emptively, plan effectively, and extend the specific rights and correct privilege level needed to everyone to do their jobs, your tenant merger effort will have a positive outcome.”
With this in mind, a basic, high-level process for merging tenants, regardless of use case, can be broken into three phases: Pre-migration, which is arguably the most critical, migration, and post-migration.
Pre-migration assessment and planning is essential to any successful M365 tenant merger.
Perform pre-migration assessment and business planning
Set up target tenant
Prepare the source and target
Configure your domain
Execute technical migration
Complete testing & validation
Clean up and organize in post-migration
Develop documentation, governance and support functions
Mergers and acquisitions (M&A) pose challenges for companies no matter their size. Microsoft 365 is the digital backbone of more than three million companies worldwide, making the scope and scale of merging M365 tenants significant and daunting. The same complexities that exist in single-tenant M365 management continue to exist but multiply in a multi-tenant environment.
Cutting these complexities down to size by gaining visibility into processes and resources in all the affected tenants and performing a comprehensive pre-migration assessment will go a long way toward making a post-merger unified tenant run smoothly. If not scoped and managed properly, the companies involved are exposed to real risks to business productivity, security, and compliance. And once again, the people angle is front and center. In an M&A situation, there will undoubtedly be IT admins, for example, who want to retain the privilege level they have always had, but, as Director of Product, Alberto reasons, “when you have two or more companies, one is going to be able to do more than someone else. Someone will lose the level of access and responsibility they once had.”
Alberto continues by highlighting some of the primary challenges faced in M&A processes, stating, “Delegation becomes even more challenging due to the lack of native Microsoft tools. As companies attempt to merge their processes, they encounter insurmountable technical constraints and they are pushed into a security versus productivity tradeoff, which most of the time ends up with the centralized IT functions of both companies becoming overwhelmed, doubling the burden.”
What steps constitute a recipe for success in combining M365 tenants after a merger or acquisition?
Aside from aligning strategy cross-functionally, involving not only IT, but also legal, compliance, HR, finance, and executive teams from both companies, it is important to assess both companies’ Microsoft environments carefully. It is unlikely that the IT teams in each company know what the other company has going on “under the hood”, that is, how is the other company’s M365 set up and managed, if at all? A technical audit and analysis can reveal how M365 is being used, the number of users and licenses, and what applications and services make up the environment. This early planning phase is also critical for identifying cultural and political conflicts that can arise within these ostensibly technical processes.
Assess target company with read-only admin
Conduct security assessment
Outline workload adoption
Inventory licenses
Map out protocols
Catalog devices
Consider full M365 operations
Secure Microsoft 365 before full tenant integration
Perform a full M365 health check
Onboard and provision M365 workloads
Maintain and optimize your tenant
Plan, plan, and when you think you’re done, analyze and plan more. The consensus among experts is that conducting a successful and safe tenant consolidation project relies on getting pre-migration planning right and taking ample time to do the groundwork properly. The best of all best practices is to invest the most time and effort into the pre-migration phase to ensure that critical information and cross-functional perspectives are captured before taking any action.
Senior Director, Solution Architecture, Simon adds, “It’s an oversimplification to say that the physical migration is just a click of a button, but it really is the easier part of the tenant consolidation. It’s the planning, analysis and getting to what you don’t know but need to know that is the hardest. Before ever starting to consolidate or migrate data, just be able to look at how tenant A differs from tenant B, and what does the work look like, and what steps are required, to make the target tenant ready for the consolidation?”
Some of these best-practice steps include:
Inventory your data during pre-migration planning
Don’t forget identity data during pre-migration inventory
Look at more than one tenant migration tool
Build in a buffer to account for overlooked inventory
Make sure your migration approach matches your needs and resources
Pre-clean your data
Migrate identity data first
Pre-instantiate users to avoid business disruptions
Understand compliance-related issues with cross-tenant migration
Director of Product Alberto notes that many large organizations approach CoreView specifically because of the significant challenges they face in managing complex tenant environments. Their primary concern is the overwhelming intricacy of these systems coupled with frustration stemming from the lack of effective Microsoft tools to manage the resulting chaos. Alberto explains, “Integrating diverse stakeholders and operational methods within a single organization is already difficult, but these challenges intensify during a tenant merger, escalating the chaos to an entirely new level.”
This is exactly the kind of chaos that CoreView was built to handle.
“Tenant consolidation often feels impossible because creating one giant tenant makes governance, delegation and automation seem impractical at scale,” explains Senior Director of Product Marketing Rob. “CoreView was designed specifically for these challenges, providing visibility and consistency, the ability to create virtual tenants and segment and delegate ‘just enough’ access, and automate tasks while striking the critical balance between security and productivity.”
CoreView simplifies and de-risks tenant consolidations by:
With CoreView, organizations can:
With CoreView, you can operate securely and productively whether you are merging multiple Microsoft tenants into a single tenant or managing a multi-tenant environment. It’s possible to overcome the IT security-versus-productivity tradeoff and enable tenant consolidation marked by risk reduction with secure, least privilege delegation and task automation to match your unique complex tenant needs.
Find out how Marcegaglia saved three days in their M&A-triggered migration process and gained efficiencies in their Microsoft 365 tenant management.
Request a demo to see how CoreView can streamline your Microsoft 365 tenant consolidation.
