If it were me, and I had asked my boyfriend's mother to make a quilt, I would go ahead and give it my sister as planned. I think in the interest of future family harmony, you can't recolor it, change it or not give the quilt as a gift unless you want to create a terrible situation between you and his mother. If you keep it, or change it , you will have a lot of fast talking to do. Chances are your boyfriend's mother will not see it in use ( or NOT in use ) at your sisters house, so whether she uses it or not would not require an explanation. Besides, as others have said, she may actualy like it!