Splitting a 365 Tenancy?

Hi,

So the situation is that a company has two branches, one local (to me) and the other overseas. Currently all the IT is based around a single Microsoft 365 Tenancy (with third party extensions for DMARC and email spam/phishing protection) administered from the overseas branch.

This is reportedly leading to some issues, the two branches have different security requirements (the local branch can afford to be more open with regards to BYOD for example), having to go through the overseas admins for almost every change is inconvenient, and also importantly some data should be compartmentalized (notably there is local information that ideally should not be visible to anybody in the overseas department, including the admins).

So having been asked to look into options, and being quite new to the inner workings of 365, after some investigation it seems prima facia that a solution might be to split the tenancy into two, moving the local office members into the new tenancy which would be controlled by a local admin, and then connecting the two possibly with a multi-tenant organization.

Obviously everyone would need to keep the same email addresses.

So, what I would like to check is
1) Is this possible?
2) Is this a sensible solution to the problem?
3) (Assuming the first answer is "yes" and the second at least a "maybe") any pointers to how to do it and any things to watch out for?

Any help/suggestions would be greatly appreciated.