cpb
I am glad you don't like the 6 months with one parent and 6 with the other. I just don't believe that children's lives should be divided up like dinnerware.
You're also right that small children have short-term memories; they live in the moment; what they have this minute, or where they are this minute is what and where they are--they don't anticipate going back to where they came from or regaining something.
It will be important for this child to get to know her father and his parents as 'safe' people so that visits go smoothly and the child is comfortable and secure.
It burns me up to see parents crying and carrying on because the child is leaving, or 'mama's gonna miss you sooo much' and they keep it up until the child is screaming and sobbing. Then, they turn around and say the child didn't want to go.
I'm 100% on the side of the children; children need both biological parents, grandparents, aunts, uncles, cousins, and family pets in their lives.
The mother may not want overnight visitation, but that's normal, too--most young parents leave babies, even newborns, overnight with grandparents, so why make a difference because it is dad and his parents (at 19, dad does need to have the baby in the home with you--in my opinion).