You'll need to transfer from one to the other. And if they have different UY, you have to be careful that you don't set yourself up for borrowing. You cannot borrow transferred points.
If you combine to use them at your home resort at 11 months then it's just the same at 7 months except you'll be able to choose any resort that has availability.
If you have different UY's you need to transfer points from one contract to the other. Those transferred points you need to call in to use and you can't seem them on your online account.
Another thing to have in mind is that you can't pool all the points, so the transferred points needs to be used to make part of the reservation. Then the other points can be used to make the last part of the reservation. This might leave you with leftover points from the transferred points.