Awwwww...that's precious. I have a 7 year old grandson who absolutely LOVES the quilt I made for him at Christmas 2 years ago. He would come out to my house and look all through my fabrics talking about all the patterns on the novelty ones. I kept telling him I was making him something special. So, I searched for fabric that showed all the things he had loved so far. He was infatuated with stars before he could even talk, loved coins, loved art, sports, etc. Then I took Moda Marbles of all primary and secondary colors, cut out a six inch square of the background color, then appliqued a smaller piece of each of the novelty fabrics. Every square is a different color. At Christmas when he opened it, he squealed, "My Quilt!!!" He was so excited and I was thrilled almost to tears that he reacted so. I know your babies are going to love anything you make for them!! How precious.
I can also share that every time I take my quilts and quilting things to school for talks about quilting, the boys are the ones who are always the most interested. I usually take a Featherweight and one of the little toy Singer sewing machines too. Those boys always tell me they're going to learn how to quilt someday.