Sharon,
You're right don't let her ruin the fun and excitement you have for your brother and his first born. Don't let her emotions of not appreciating the love and artistry that goes into making a special quilt for the baby cross over into your excitement. Make one even if you have to go and see her PB decore before you pick out a pattern and colors and make the quilt you want for your nephew or neice, you don't need her permission. If you find she never uses it then wait until the little one is older and can appreciate the quilted blanky you make just for him/her and you know the baby will appreciate the love that will go into a quilt you make special just for them.