Additional SQL Server features and topics not covered by specific categories
If you're creating a new login (such as a new login for an account in DomainY) then you'll need to create it as a login on all the SQL Servers you'd like that login to have access. There is nothing stopping you from scripting out the login and associated users, then changing the name for the DomainY items, but again it'll all need to be created. If SQL Server changes domains, then you'll need to have trust relationships in AD with those domains.