Two Sub Domains

[setthecat]

I currently have a simple domain controller but will be moving soon and plan to restructure. I want to have one domain controller in my apartment and one domain controller in my mom's house that will be able to communicate with eachother.

I know the kosher way would be:

SetTheCat.local

-home.setthecat.local

In this setup would all accounts be name@setthecat.local or would users in the subdomain be name@home.setthecat.local?

But I was wondering if I could get the same advantages with:

apartment.setthecat.local

home.setthecat.local

Also, with this setup, would my user accounts be set@setthecat.local or set@apartment.setthecat.local?