I didn't say "when she has a kid." I said "when the other grandkids get married." No one's saying she's not part of the family or that she somehow earns her place by having a baby as far as I'm seeing in the post, but it matters (imo) what rule gmil is following that's resulting in op feeling singled out. If op's husband's cousin gets married and suddenly there's a family photo with grandparents and aunt and uncle and cousin and cousin's partner on grandma's wall, then OP is right and has a very legitimate grievance; if cousin gets married and now there's a grandkids-and-their-partners photo that she's included in, then it was just that one person isn't a "group" that occurs to anyone to take a separate group photo about and it was never about her personally.