Finding the words in open adoptions

DEAR AMY: My adopted daughter has given birth to four children, and now she and her husband are going to adopt a baby boy. She invited me to her home recently where the biological parents (not married) of the expected child and the bio mother's two other children came for a friendly visit. All the children played with one another in a friendly manner. This will be an "open adoption," where the birth parents will have opportunities to visit the child. Here's the tough part. What is the name of the relationship of the two sets of children? They aren't step or half anything because they don't share bio parents. What are the relationships between my own grandchildren and the mother in Family B? I assume they will simply call her by her first name. Has society initiated names for these relationships yet? Will the baby boy have two mothers and fathers? Please ask your academic sources for some help with these questions. Grammie

DEAR GRAMMIE: Deborah Tannen, professor of linguistics at Georgetown University, says, "English lacks words for many family relationships that other languages have words for, and the words we do have make far fewer distinctions than do the words in languages that pay more attention to the subtleties of family relationships. I guess one could try to come up with words for the children who share parents and siblings through a series of adoptions, but I'm thinking that such words have not yet been developed, and perhaps don't need to be.

"Many people I have interviewed in my research simply used 'children' and 'siblings' for those acquired by any means, and didn't mention the distinctions unless it became necessary for points they were making -- in which case they had the time to explain the subtleties."

I completely agree with professor Tannen. The intimate circle of people involved in these relationships know who they are and how they are related to one another, and beyond that it is only rarely necessary to explain further.