You're not making your SIL a quilt, you are making the baby one. You don't quilt because it is an easy way to come up with gifts, you do it to show you love someone and to share your passion for quilting. Go ahead and make what you like, not like the baby will only use one quilt in her life. Maybe even make it bigger, like twin bed size, that way it won't need to match the current scheme, and when the kid gets older he/she might want her room to match that quilt they love that their aunt made.