Why do you have an AP that expires on 12/02/04 plus PHP--
Actually--if they backdate it to the first use of your PHP then the whole purchase price you paid will be applied. I think that is how it really works as we traded in a Fla Resident Play 4 days pass for a Fla Res Seasonal pass and it worked this way.
the "extras" will not matter on the trade in as an annual pass has no "extras".
So, say you use your PHP on August 15th and again on the 16th...and then you didn't use it. On September 15th, you are coming to disney again, but you wish to upgrade your pass. You paid $250 (fake number!!!!) for your 4 day PHP. On September 15th when you go to upgrade, they apply the $250 to your AP rate and you pay the difference. But you annual pass date is August 15th and not September 15th. In other words, they don't divide the cost of the PHP by the days on the park hopper pass and then credit you for unused days towards a pass.
We did this last year with a 4-day pass...my hubby bought the Fla Res Seasonal pass in October--but the anniversary date was July--on the date the first pass used.
Make sense?
Good news is that you won't have to pay much out of pocket as long as you do it before midnight on the final usage day of your PHP.
However, it sounds like you need to call the number listed on your tickets, b/c another poster says you can pro-rate the days--something I haven't heard of before-but then again, I am in the world of Fla Residents and our rates and tickets are different.