Part of the reason Barb hasn't tried to forge a connection with Ensley is that she is, after all, UBT's child. That relationship is already fraught, her entering into a relationship with the baby daughter would trip all of his wires. She may also feel that Ensley is a bit protected from the worst of it, as a girl, and will only suffer from the general neglect and abuse present in the environment. (Not saying I agree). Also, she does have her hands full.
It occurs to me that Chelsea and Aubree have been the only ones there for each other during the whole entire experience of Chelsea's motherhood. In a way. Randy, Chelsey, Landon and all the rest are amazing support, and now Cole is in the full time Dad mode... but Chelsea and Aubree have created this routine together from the beginning. Wanting to share the latest experiences with her must feel natural in a way. Aubree is very caring with Watson, and is very cared for by Cole... but some of the single mom roots of their relationship are sticky. I think it's nice, and I hope they continue to be close.