I know, I was bummed as well. I have all the fixings ready to go, to make 3 pillowcases for our friends kids that are sailing with us. I was talking to Solaryss yesterday about this, because she had just purchased pillowcases for her kids.
I suggested that she still could create a magic moment for them, and you could as well. This does all depend on how crafty you are though. You could get plain pillow cases for the kids (in addition to the autograph ones), and find the autographs you want to use online. Once you have the autographs, you can make a print up of them. There are 2 different ways you can go about adding the autographs. First, if you are confident in your copying skills, you can use the print up as a guide, and sign the pillowcase with fabric markers. The other option is to use fabric crayon transfers. With this option, you would print the autographs in mirror image, and then use the iron transfer crayons to trace the autographs (make sure to cover each letter completely, and do not make any stray marks). Once the autographs are traced, you place them colored side down on the pillow case, and cover with a second blank sheet of paper. It only takes a few seconds of heat and pressure from your iron to transfer the images. If you decide to do the 2nd method, I would suggest practicing a transfer onto a scrap piece of material first.
Now, armed with 2 pillow cases, you can make sure your daughter sees you put the plain pillow case on the pillow, and then at some point sneak back to the cabin, and make the switch. By the way, the pillows for the hide away beds are usually kept in the storage box in front of the couch.
Another option that just crossed my mind as I was typing is that you could also find your room steward, and ask them nicely to place the autographed pillow case on for you.
I hope this helps.
~Tink~