Basically the idea is to copy and update 1 OU in the master Domain into slave Domain. The OU will have users and groups in it. If a new user is created in the master domain they will be created in the slave domain. If the user changes there password in the master domain it will update in the slave domain. Note: users don't change their password in the slave domain.
I have currently setup an import MA for the master domain and an export for the slave domain in my dev environment. If I configure the attribute flow I can get update attributes in the slave domain from the master.
I am open to suggestions for other software that will achieve this goal.