I am not sure but my impression was that it is a September UY. If your other contract is a feb. UY, you will have 2 different contracts, 2 different member IDs, 2 accounts, etc
If I understand your question, you currently have a DVC contract with a Feb UY, are looking at adding another with a Sep UY, and want to know if DVD will somehow merge the two into the same UY.
If that's your question, the answer is no.
You would have two different UYs with two different membership numbers. There are various threads which discuss the pros and cons of this sort of arrangement.
It w/b up to you to buy (I'm guessing resale since DVC would automatically match your current UY with any direct add ons) another contract with your existing Feb UY. Then if that new contract was titled exactly the same as your previous one (down to middle initials), you'd keep you exiting membership number. If you title it differently (like only in your name but not your spouse while the original contract had both) you'd still wind up with two membership numbers even though you'd have the same UY for each.
No. Those Sept points remain Sept points. They cannot become Feb points. You need to purchase a Feb UY contract if you want the new contract to be an add-on to your first contract.