A mother is a parent. The one who takes care of a child, preferably along with the father. Like I said, I agree with your point, and having 2 mothers cannot possibly be good for these babies. I just think that it is fine for someone to call themselves a mother, without being genetically related to the child.
A mother is more than a parent. A mother is someone who plopped you out of her body. There are step moms, foster moms, adoptive moms, etc, that all can reasonably referred to as “mother” if the real mom, for some reason, is out of the picture. This, apparently is not the case here. Real mom is there. Wanda is the girlfriend of the lesbian mom. That’s it.