Multiple Companies in one Tenant

[Anon1m0us613]

I have company A that owns Company B, C, & D.

I would like to create one Tenant for Company A and add the domains of Company, B C, & D to it. This way everyone in that company can easily share files between on another. ALso, user creation is simple.   For example, the Sharepoint site will be http://CompanyA.onmicrosoft.com/CompanyC *&  http://CompanyA.onmicrosoft.com/CompanyD.

Is this something that makes sense?

[#2]

You might be able to create one company domain and add multiple groups inside the same company. So, they are all inside the Company A, but they have different access and permission. Another scenario is to create domain for each company and share resources across them. In case you are using SharePoint, you may create one domain and add multiple websites and share resources for each group.