So if I use my one transfer per use year I could transfer all of my points from one use year into the other and then use all my points to make one reservation? Or maybe just use banking and borrowing and use one membership one year and the other the next
Yes, you can transfer from one membership to the other and once you hit 7 months (if different resorts), you can then book using all the points.
Or, as you said, use banking/borrowing. I think the key, however, if you are going to go with two UY's is to know how many points you would need to have in each contract to book some of your nights with each without having to bank, borrow, or transfer.
We had two UY for a short time. One contract was 130 and the other was 50. Our typical summer trip is 6 nights. The 50 point contract was not large enough to book two nights without borrowing. The same thing with the 130--not enough for 5 nights without borrowing. I realized that at 11 months, I would only be able to book 5 nights, instead of all six unless I borrowed points.
Now, had the smaller contract been 75 points, it would not have been a problem.
So, when searching for that 2nd contract, just make sure it is big enough to book all the nights you would need it to book in conjunction with the other contract.