Update:  I think I'm just going to try to get used to the idea that it's a possibility so that when it happens it won't bother me so much and I'll just be able to say. "No, not my grandchild(ren); they're my own child(ren). Kinda like I do with my SO now. People say "oh I saw your son", I say "Oh he's not my son, he's my fiancé" and I don't feel bad or upset about it because it's only natural for them to think that....he is young enough to be my son. I'm going to try to have the same mindset when it comes to our baby.