3 Sites?

Hi, I hope everyone is well.

I am in the process of making a membership site and I was wondering if this software allows a member of the site to be able to login to site b? So when a member signs up they can access a different domain and login there as well.

Just trying to make it easier for the member. I have read you can import a CSV file with users names, but can I install the plugin on 1 main domain and 3 different sub-domains, and have the member become a member of each one and be able to sign in without signing up again for each sun-domain?

Any help would be great,

Kind regards,

David.