Merge of 2 seperate 0365 tenants

HI 2 Organizations to merge into 1 o365 tenant.
I would like to use 1 Ad connect server (ours) to synch the 2 domains into the 1 tenant to allow the 2 disparate domains (both complete separate dns namespace)

Now both orgs are in separate tenants . AND both have hybrid exchange online.
Now Ive been told that as we "both" have hybrid exchange online - that we will be unable to merge into the 1 tenant.

I would like to know if this is true and why please
LVL 1
philb19Asked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

timgreen7077Exchange EngineerCommented:
That is correct. You can't merge 2 separate tenants into 1, but review the below link for supported topologies

https://docs.microsoft.com/en-us/azure/active-directory/hybrid/plan-connect-topologies
Saif ShaikhServer engineer Commented:
You can use migration Wiz to accomplish the task.

1. Add users in the migration Wiz with source and tenant.
2. Create users manually in the target tenant with on Microsoft.com domain.  
3. Run N initial sync using migration Wiz which will sync all mail items. Calendar and contacts will be synced in final cut over.
4. Remove smtp domain from target tenant and add the domain in source tenant.
5. Add the added smtp domain as alias for all manually created users who are in the migration Wiz batch.
6.Run final sync.
7.. Point all my,  autodiscover records for the domain.
8. Change the primary email address for all migrates users to ABC.com
philb19Author Commented:
That is correct. You can't merge 2 separate tenants into 1, but review the below link for supported topologies

I understand that you can - "play on words" - the end goal is to migrate the AD user objects into the 1 (our) tenant.

relationship - 1 AD connect (ours) - pulls in (has access to) their domain and we add in their emai domain to our tenant once completed.

That's what I have read - is this wrong? thanks
Big Business Goals? Which KPIs Will Help You

The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

timgreen7077Exchange EngineerCommented:
yes you can add their email domain to your tenant. you must first remove the domain from their tenant first. once that is done you can add the email domain to your tenant and sync the user ad objects if they are members of your domain or a child domain.
philb19Author Commented:
"if they are members of your domain or child domain"

So I would need to migrate the AD user objects into my internal AD  domain first?

how would their exchange online manage with this change ? - isn't there a step by step migration for migrating off 1 tenant to another (with 2 separate exchange online orgs)
SysToolsData Expert - Recovery,Backup,MigrationCommented:
You can use the manual method to Merge two separate 0365 tenants as mentioned above but it very complex to perform it. Since no need to worry as you can use Office 365 Merger Tool for the better merger.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Exchange

From novice to tech pro — start learning today.