Before my husband and I met he was in a relationship with an older woman who had a child. The child was 11 when they met and was in her early 20's when they split up. She doesn't know who her biological father was (her mother either doesn't know or won't tell her). My now husband has been 'dad' to her for many years now, she's now in her early 30's, calls him dad and they have a normal father/adult daughter relationship.
She lives at the other end of the country but visits regularly and my family have embraced her as part of the family, with my parents joking she is the closest to a grandchild they'll have as both myself and my sister are child free.
She met her boyfriend a couple of years ago and they are now expecting a baby in the new year.
They and my husband are referring to him as 'grandad' but he keeps jokingly calling me 'granny'. He has done this in their presence and they seem to be OK with that. However even though she doesn't really get along with her mum, she is still most definitely in their lives and I am very conscious that this baby will already have a granny (2 in fact) and even though I've never met her mum I don't want to be seen to be usurping her. Any ideas what baby could call me?