I have never been able to combine my disney gift cards together. I have tried calling the number on the back of the gift cards and I have tried asking at the Disney store but both said no. It would be really nice if they would allow it but I didn't have a problem reading the numbers out over the phone for my cruise and once there they let me scan as many gift cards as I had to pay for things.
I have tried to combine them also, without any luck. And I buy $25 and $50 Disney GCs every time I can fit it into the grocery bill. Tried to buy a wrist GC at ECPOT for F&W and could not...so I am going to punch a hole in the corner of each one, attach them as I need them to a wristlet to use them at the next F&W trip this fall.
I have combined several recently. I called the number on the gift cards and the cs agent said they can not do it but I could take them to the Disney Store and they could call the merchant line and do it. When I went to the Disney Store they said they had been doing that a lot lately and what they were doing was cashing my g.c. out and then having me buy 1 new gift card with the cash. I have done it a few times in the last few weeks and the 1st time I had 7 or 8 gift cards to combine. Hope that helps if you have a disney store close!