What do in-law grandparents refer to each other as a group
What are grandparents of the same child from the mother's side and the father's side refer to each other as....Say " I am so looking forward to becoming..co-grandparents, grandparents-in-law, etc. with you"?
I would just say "....looking forward to becoming grandparents together with you". I don't know of a specific term for that relationship, but I think everyone would recognize that all 4 are grandparents of the child. So I would just go with "grandparents together with you" even though it is a bit clunky.