We have a 3yo and I’ve never told him about my parents, of which I am now NC. My DM has seen DC twice as a baby and DF not at all. Both live in long-haul destination country.
DC sees his paternal grandfather weekly and paternal grandmother passed away last year but I think he slightly remembers her. I’ve just never told him, and presumably he has never learnt, that most people have four grandparents.
I just don’t know whether to leave it and wait to see when he asks questions, or tell him I have parents too who live a long way away but I don’t have contact with them - and then I’m at a loss as to what I could say in an age-appropriate way of explaining why etc.