They will both be home resorts meaning that you will owe dues at Polynesian rates on the Polynesian points and be able to use them to book the Polynesian 11 months out. You will not be able to use any SSR points at the Polynesian until you are within 7 months of check-in.
ETA: Any resort you purchase becomes one of your home resorts. The significance of a "home resort" is that it determines the end date of the contract, the dues rate owed on the points owned at that resort and provides you an annual allotment of points you can use to book that resort (and no other) 11 months from check-in or any resort 7 months out. There are other implications too. For example you are a DVC Member only because the resort you own (SSR) is part of DVC. If SSR was sold off, you would no longer be a DVC Member but would be a member of some other timeshare group.
you could also look at it as "the home resort booking advantage belongs to the points and not you as the owner."
if you add-on a 25 pt contract at the poly and wanted to book the poly at 11 months out, only pts from that 25 pt poly contract would be valid for use...so you'd max out with 25 banked poly pts + 25 current poly pts + 25 borrowed poly pts = 75 poly pts every third year.
but your SSR pts would continue to stay on the sidelines for booking at the polynesian until you get to the 7 month window.