Flitterific -
Well, here is my experience with that sort of ticket ugrade/swap situation:
Two years ago, I had accumulated a bunch of one-day/one-park tickets (the kind that used to be $66, then $69, now $72). A client of mine, who did a lot of charity work, used to buy them for sick kids so they could go to DL. She gave me some of the tickets as a thank you for the work I had been doing for her. The one-day/one-park tickets have no expiration date.
I wanted to get an AP - a PAP, to be exact. I called DLR and asked a CM if I could combine a few of the one-day/one-park tickets I had towards the price of
one PAP. She was not sure. She asked another CM, who said she thought it would be okay to do that. But then they put me on hold to call the
Disneyland Bank to be extra, extra sure. I was glad that they were taking the time to find out, so I wouldn't waste my time later trying to do it if it was not okay. They came back with a big YES from the DL Bank. The DL Bank CM said that "
as long as those OD/OP tickets are unused and unexpired, then Disneyland views them as if they were money, and that total value of the tickets can be applied towards one AP or one Hopper or whatever." Excellent!
So I arrived at DL and marched up to the ticket booth to hand over 3 of my OD/OP tickets. The surly male CM behind the window instantly said NO, I could not use 3 tickets towards ONE PAP. I argued (politely) with him and said that, indeed, I could. I told him that I had been told very clearly by a CM who checked with another CM who checked with the DL Bank, that it was fine to do this. I named names of CMs so he would know who to ask. The surly male CM growled, "Well, not if they're used. If they're used, you can only use one ticket towards an upgrade."
I said, "But they are not used. None of them are used."
Surly male CM growled again and said, "Well then
it's not an upgrade, it's a swap." And he scanned each ticket to be sure I had not used any of them. He reluctantly applied the total value of all 3 OD/OP tickets towards my PAP, and I ended up getting more than 50% off of the total PAP price that way. I only had to pay something like $191.
Fast forward to 2009. Once again, the client I mentioned above gave me more DL tickets - the OD/OP kind. Instead of an AP, this time I wanted to use 6 of those tickets and "swap" them (not upgrade, as I was reminded by the surly male CM in 2008) for three 1-day Park Hoppers. I called DLR beforehand to be sure the Bank was still allowing this and still viewing the unused, unexpired tickets "as money." They confirmed that I could still do this.
In October, I marched up to the ticket booth again, 6 tickets in hand, and gave them to the nice CM in the booth. I explained to her that I already knew a "swap" could take place, and the tickets had neither been used nor had they expired. I asked for three 1-day Hoppers. She scanned them to be sure I was telling the truth about the tickets being unused. She said, "I have to check with my supervisor, because we're really not supposed to do this."
I said, "But the Disneyland Bank said..."
And the friendly CM said, "Yeah, but we're really not supposed to do it."
So while the CM was conferring with her supervisor in the back, I was worried that they wouldn't let me "swap." She returned and said I had a "balance of $123." I nearly fainted. I thought she meant that I had a
balance due of $123. What she actually meant was that the 6 OD/OP tickets, all tolled and applied to the price of three 1-day Hoppers, had a $123 balance left over. I expected nothing of this. I just wanted the 3 Hoppers. But the friendly CM gave me my 3 Hoppers AND a gift card for $123!!!!!!!!

So, I guess the reason I am telling you all of this is that, based on my two experiences with these kinds of ticket swaps, some CMs will say it's okay (usually the ones on the phone who take the time to check with the DL Bank), but the ones at the actual ticket booth seem to not want to do this, or they don't know that they are allowed to do it.
So you may, perhaps, have trouble if you try to combine GAD and LMT tickets towards the price of an AP. Or you may not. Yours would be discounted Hoppers with expiration dates. Mine were regular-price OD/OP tickets with no expiration date. The CMs may handle the discounted Hoppers differently and may not view them as money when combined together. They may only take one of those tickets and do an "upgrade," but not a swap. What you want is a swap, not an upgrade, if you combine tickets.
I would do what I did and call DLR first, explain what you want to do, that they would be discounted tickets from GAD and LMT and have them check with the DL Bank. Make sure you stress that the tickets would be
unused and that you want to
swap, as those seem to be the key words. Otherwise, they automatically assume that the tickets/Hoppers will have been used and that you want to upgrade, so they will say you can only use one ticket for an upgrade.