Twin girls, huh? All pink could be just one fabric for the back and one for the front, but I suspect that is not what your friend has in mind!
May I suggest using a Hello Kitty Panel and go from there? I don't know any young girls who don't love Hello Kitty!
Another idea is to make a chevron quilt with pink and another color. I made one in a peach print and a coordinating brown print and hated to give it to the baby. But I did.
Last suggestion from me: Get a couple of alphabet panels and cut the letters apart, sash them and put a nice border on them. Sashing and borders could be different so the girls can tell them apart.
Have fun!