Thanks to all of you for taking the time to reply.
I agree that my daughter shouldn't be making the decision about the pattern. I think i will show some quilt patterns to my granddaughter and see which one she'd like. Now why didn't I think of that???
I also like Tartan's idea. I never would have come up with that. If my granddaughter gets on the computer and finds a pattern which won't work with the 12" squares, then I'll use the signature blocks as the backing.
Thanks again! You guys are great!