You have to transfer points between contracts in order to use together and you can do that each UY for that one and the next one.
Transferred points don’t play nice online during the home resort booking g period, even if the same resort so it does require a call.
You also won’t see them except when you go to book since they are held in a temporary contract.
And transferred points can’t be borrowed and they retain all their own rules. So April UY points stay April UY points even if you transfer to the Feb UY.
That means you have to think carefully of when you want to travel with them before deciding which ones should be transferred.
Also, banked points can’t be transferred so keep that in mind..although MS did transfer 5 banked points for me last year between my memberships after I added on new points direct. It may have been pixie dust but they do tend to allow owners more leeway when moving points between their own membership but that does not have to happen.