Since you are in your 2016 UY, you would get all points starting in 2016 and forward.
No. By definition, an add-on gets added on to your existing account so it must be the same UY. If you purchase a contract with a different UY, MS sets up a new membership for you and sets up the new contract as a new master contract. While you can purchase an add-on as small as 25 points, in the past there were higher minimums for new master contracts but there have been times when they have been willing to sell as few as 50 points as new master contracts. I'm not sure what the minimum master contract is at the moment and it may vary depending on which resort you are purchasing.
You can ask but I don't think you'll have any chance of success. While it does have a slight affect on the value, it really doesn't have that much of an effect. I can't think of any situation where the extra year of points banked to the next year would be make or break. If you're set on Poly, need the additional points but not right away and can pay for them; you might keep your ear to the ground for price increases with the intent of waiting until just before a price increase or just before the end of the UY in 2017 so you'll save on the dues for the same points. You will have less time to use them. Or you could look at a resale option that might be cheaper/better value depending on your ultimate goals.
Bill
I would not buy for one trip. This is an example of a point I've made recently, the push to buy quickly causing one to over pay. In this case it's be very expensive points for a single trip. IMO paying cash, renting privately or paying for a transfer would all be far better than this plan. Now if you're set on buying the Poly anyway and this would be a bonus, it's a different scenario.
True, unless you can find a resale contract that has 2015 points...
That's true in general though the OP was really about buying retail and getting 2015 points with a June UY though they didn't spell out a retail purchase. A loaded contract resale is generally the best deal as you state.
If you don't need Poly for 3 years then it's likely not a good choice for you anyway. Make sure you look at cash options both through DVC and through Disney directly with discounts. You are likely better off renting from another member rather than transferring due to the timeframe involved and number of points needed. You might consider a cash reservation then a resale add on if you actually need the points long term. Then you could see if you could reserve with points once you have them but have the cash reservation for backup. You just need to be sure the cash reservation is something you can live with if the other doesn't work out. You could always rent out any points that you would have used from a resale but couldn't/didn't to offset your costs. For a one time trip it doesn't make sense. Of course you could buy Aulani and tie your purchase to the reservation if you felt retail was worth it, it usually isn't.
