I've been struggling with trying to find a way to tell my dad and my step mom who are both going to be first time grandparents.

I bought my dad a mug that says Opa, but I can't think of the perfect gift for my step mom. I feel weird because she has 3 of her own kids and I would feel guilty taking away that "you're going to be a grandma" moment from her kids.

They really like puzzles, I was thinking maybe if making a crossword or a jigsaw puzzle that would reveal that they will be grandparents and then give my dad the mug and maybe find just something nice and generic for stepmom to avoid the "grandma" situation?

Any ideas? How did you tell your first time grandparents to be?