For a trip in March 09 you can use any of the following points for that stay:
From your Aug UY contract: Aug 08 points, banked Aug 07 points, borrowed Aug 09 points.
From your Dec UY contract: Dec 08 points, banked Dec 07 points, borrowed Dec 09 points.
Since you are in the 11 month booking window you need home resort points to book that trip now. Since your contracts have different use years, you cannot combine points from both contracts. You can book part of the trip with one contract and the rest with the other and link the two reservations together. You can also transfer points from one contract to the other provided you have not already used up your one transfer per use year on either contract. If you decide to do that, be careful about the order in which you do things. For example, you cannot transfer banked points but you can transfer "current" points and then bank them after you transfer them.