visits

My son and his wife are adopting, they have had custody of the child since she was 8 months old - now she is 16 months old - the birth grandmother had legal custody, although the mother was somewhat involved and the three of them had an on again, off again relationship. A week into the adoption - this is an across the state line adoption, so custody was given before the states had all their paperwork completed, the birth grandmother continued keeping the child until the paperwork was completed - a whole month. They had time to look at this and were asked repeatedly by the adoptive parents if they really wanted the adoption. She was to have visitation at the adoptive families home and would be treated as a grandparent. The birth mother wasn't supposed to have contact. Really, too much time in between, but two weeks after the transfer of the child to the adoptive parents, the birth grandmother decided she wanted her back, then the birth mother called and said she just wanted them to bring her back home. Harrassing phone calls beganwith from the birth mother and threats from the birth grandmother started and contact was stopped. Lawyers were called and now 8 months later they are down to a sort of mediation. Now the birth grandmother wants over the weekend visitation at her home without the adoptive parents - four times a year. They have had two short afternoon visits - it gets more and more complicated. I wonder, are these over the weekend or overnight visits a normal part of open adoption and at what age. A 16 month old away from her adoptive parents seems rather ridiculous to me. I just really want the best for the baby, but I have to admit I would like to see my children happy with this and they are miserable about letting her spend the night away, although they would do anything to get the adoption papers signed. Thanks