How to merge Office 365 tenants without the headache

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Are you an IT admin gearing up for an Office 365 tenant-to-tenant migration as part of a merger or acquisition? While the project may seem daunting at first, we’ve put together key information that will help you get it right.

In this article, we’ll go over common merger scenarios, the two key steps to a successful migration, some tried-and-true best practices, and a comparison between manual and automated migration.

By following these tips, you’ll make sure that your tenant-to-tenant migration project runs well—so successfully that you won’t have to break out the Tylenol for any stress headaches!

Let’s start with the two most common scenarios for an Office 365 merger.

Which Office 365 tenant merger scenario sounds familiar?

To help you systematize your knowledge and turn the initial idea into a plan, check what resources come up in each scenario and what tasks should land on your migration to-do list.

Hint for the busy IT admins: if you’re planning a simple merger, go straight to the first scenario. If it’s something more complex, the second scenario will accommodate you better.

1. Tenant-to-tenant migration

Say your company just acquired a company called Alpha. Company Alpha has its tenants in the cloud—just like you. And to top it off, your business wants to rebrand the newly acquired company.

Your main task will be to migrate from one tenant (the one that belongs to Company Alpha) to a target (already inhabited by your company).

There are a couple of other points that should land on your migration to-do list, too:

  • Change the original domain of Company Alpha to your company’s domain.
  • Create a new target tenant for Company Alpha so the rebranding goes smoothly.
  • Change all user identities, documents, and accounts to new user accounts and identities (according to your company’s guidelines).

For a Microsoft Teams tenant-to-tenant migration, there are 2 surefire ways to ensure everything goes smoothly.

2. Multiple tenants migration 

Say your Company Gamma is going through divestiture and bought two companies, Zeta and Eta. Company Zeta has an on-premises setting and Eta is already in the cloud.

As for selling the Company Gamma’s subsidiary, you have to clean up your target environment and remove any obsolete accounts, users, and domain user data. 

In the case of Company Zeta, Company Gamma has to migrate the on-premises setting to the cloud and merge two tenants. As for Company Eta, the process will be simpler.

The goal of migrating multiple tenants is to join many organizations into a single tenant while restructuring some parts of Office 365 so it doesn’t contain divested environments.

In the complex arena of merging Office 365 tenants, one of the most significant hurdles can be OneDrive tenant-to-tenant migration. It’s a process that, when executed correctly, can save your organization both time and resources.

Two steps to merge Office 365 tenants

So, you say you’d like to stay on top of the migration project and be helpful for your users while causing as little distraction to their work as possible? We got this—here’s a quick and easy two-step cheat sheet to make your tenant-to-tenant migration a breeze.

1. Plan the merge and check your scope and inventory

If you’d like to move past any migration hiccups, make a detailed plan for the merge. A source analysis report might be a good idea. You’ll get details about the total number of sites, site collections, workflows, and information about what issues you need to fix before the migration.

Next, audit your current environment to get a better understanding of the versions, configuration, permissions, and state of domain users data.

If you’re doing a big migration, you may experience Microsoft 365 throttling. This is just a control measure to regulate the speed at which data is transferred to Office 365, so no need to worry about it.

2. Choose the migration approach and get your new environment ready

Once you’ve chosen your migration approach (manual or automated), focus on the users, accounts, and files that need to be transferred to the target environment. Check your target environment’s structure and keep your migration management plan within reach.


Tenant-to-tenant migrations

How to efficiently plan and execute migrations for mergers & acquisitions or a reorganization.

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Best practices for merging Microsoft 365 tenants

Check out these two best practices before moving from one tenant to another.

And don’t forget to reference out Office 365 migration checklist to ensure you have everything you need when starting a migration.

Keep the communication with end-users clear

Keeping your end users well-informed about changes paves the way to successful tenant-to-tenant migration. Address their concerns, explain the benefits of the merger, and support them throughout the process.

Show you’re going to protect your domain users data with a rock-solid communication plan

  • Set deadlines for your end users’ work so you stay in control of the operation.
  • Encourage your end users to tidy their source tenant space.
  • Inform them about which users, accounts, files, and records will be migrated when moving tenants
  • Inform them about the document structure in the target.
  • Show benefits for your end users that stem from merging tenants.

Prepare your source and target domain

To have a smooth Office 365 migration, organize and tidy both the source tenant and target tenant.

First, check if there is enough space in the target tenant’s domain for data from the source tenant. Allocate new licenses in the target tenant environment. Check if there are administrator accounts in both environments.

If you’re planning to use a third-party migration tool, manage admin accounts inside the tool. It may also save you the hassle of managing permissions; for example, the ShareGate migration tool automatically maps users at the destination, so the right people have the right access and permissions in place.

Lastly, double-check which sites, users, and accounts will be a part of the migration and which won’t. This will help you smoothly transfer desired resources to a new environment.

Third-party migration tools vs. manually merging Office 365 tenants: Which approach should you choose?

As there’s no native Microsoft solution to move data between tenants, you can either migrate tenants manually or with the use of a dedicated migration tool that will automate much of the work for you.

See how both ways compare and decide which is better for your case.

What are the risks tied to the manual migration of one Office 365 to another?

If you’re hoping to save on costs by performing a manual Office 365 tenant merger, you should know that this method has some major flaws. 

These are the most common pitfalls of manual tenant-to-tenant migration:

  • It is complex (meaning: difficult to coordinate) and takes a lot of time, you’ve got to use a different csv file for everything.
  • It isn’t secure and involves human error.
  • It involves Office 365 end users (even non-technical ones) that have to follow strict procedures.
  • It can take a ton of time. So much time that you’ll be paying your staff or consultants to work on it rather than other projects for months.

On top of that, although you can write scripts that will help you move forward faster, you still have to check if the syntax of your code is correct and returns the values that you want. So this partial automation may become overkill.

In summary, manual migration might take a lot of time and the outcome is hard to predict.

Some third-party migration tools, on the other hand, make merging two tenants easy. Check out how different your experience could be when using a tool that automates your migration.

How ShareGate can help you merge Office 365 tenants

The ShareGate tool helps make your migration simple, secure, and straightforward. It’s like this: we take on all of the hard work of migration to a new tenant from one or multiple source tenants. You just have to execute your migration plan with a couple of clicks.

Your migration process will be automated and free of errors, delays, and stress. Also, it means you’ll be able to find and fix issues fast, govern your tenants securely, and empower your end users through collaborative automation.

Take a look at the short video that showcases the migration process:

Say your task is to migrate the source tenant into an existing tenant. You have to copy the whole structure and content:

  1. Fill in the source site address (the source tenant).
  2. Fill in the destination (the target tenant).

The next step gives you a lot of flexibility: you choose which site objects you want to migrate. You can choose sites, lists and libraries, content types, SharePoint Online groups, Teams, and more.

Then, just make sure everything looks good. Use simple drag and drop actions to move components from the source tenant to the target. Now you can start copying. It’s really that simple.

What’s more, you can simplify your SharePoint and Teams migration today with ShareGate’s top-notch tenant-to-tenant migration tool. Say goodbye to complexities and embrace a user-friendly experience.

Merge Office 365 tenants—no matter how complex your project is

Although merging tenants involves different options, variables, and complexity levels, when well-planned and with the right tool, it can be easy. As an IT pro you want to stick to what works—every time. So, why not migrate everything with a versatile tool that does the heavy lifting for you?

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