My oldest grew up calling GG uncle. As an adult, she calls him by name, but if she's explaining who he is-she says he's her uncle.
The youngest is his biological child and knows that she calls him by a petname that is a variation on his given name with "MY" added before it-her choice, we had nothing to do iwth it.
The middle child calls him by his given name and sometimes explains him to others as his uncle, sometimes as "moms boyfriend". Don't know what his criteria is for differentiating-never asked.
They all call my "sister" Auntie or Mimi. She isn't biological or legally my sister-but she did live with me through middle school and highschool and we identify as sisters.
All of the kids call me mom-and all of the kids call Maca dad-regardless of biological ties (some aren't mine biologically and others aren't his).
The oldest grandson calls Maca "papa" and me "grammy" (his choice) and he calls GG by the name our youngest child uses (not including the "MY") and "papa" depending upon what he wants and what he's doing. He also knows my "real name" and Maca's and will use them if we aren't responding for some reason when he says papa or grammy. He's 2.
It's telling to realize that we are totally out and all of the kids and grandkids know that we are romantically tied (maca/me & gg/me) even if they don't know the terms sexually or romantic.
It's also important to note-that regarding additional partners-we don't introduce them at all until a solid friendship has been created (3-6 months) and we don't open to overnights or sexually suggestive (kissing, hand holding, cuddling) in front of the kids: until they have already established a solid committed relationship as partners.
Maca did twice-and it was a NIGHTMARE disaster with the youngest child. So we made that agreement for our daughters sake.