I think adding batting to a baby quilt that has a minkee backing would make the quilt too heavy. I like my baby quilts to be lightweight, after all they cover very tiny kids.
I make a lot of string quilts for charity using a large square of fabric as the foundation for each block. Between the foundation, fabric strips, many seams and lots of thread the blocks are pretty heavy. I skip using batting and back the quilt with flannel. Quilt is nice and cuddly without being really heavy.