I'm not sure of the rules(I know you can have only 1 mas), but for the ones I've done this is how I did it. Order UCC license manager. Created an app record and apply license to it, this becomes the Group ARID. From within this record, add the records to be managed by the group. Assigned the UCC licenses to the group and they are distributed from there.
I haven't done any with a separate UCA, only MAS and MCD.
UCC licensing basically sucks. When you add a user to MCD, you have to make sure you choose multi device during creation, then go to groups and add the new extension in the multi group. You can then go and add multicall keys etal. I haven't done the new dual thing in V6, but it looks interesting