I am a breast cancer survivor, Thank God!
The pink ribbon pins, cups, hats, socks, shirts, etc are fine and I have not problem with them, however, I do not think I would want the back of my quilt full of them.
I am also a quilter and I have a block that is the pink ribbon and some day I will do something with it, but haven't decided yet exactly what that will be?
I use 100% cotton fabric for quilt backing, living in the South I don't have much use for flannel on my quilts. Ask your sister and let her know you care, enough to ask bet she will tell you.
delma