By all accounts he seemed to have come from a traditional Italian, Catholic family, so that would indicate that he probably did have kids. Also, being of the same religious background and decent, it is most likely that the whole family - including the kids and proabably extended family too- were invited to the wedding. I am going to take a look at that episode (although I agree it was a bit diturbing) and see what I can come up with. Great insight!!!
I admit I am neither Italian nor Catholic, but it's a good point. Maybe Columbo and his wife couldn't have kids? Then again, No Time to Die (of all the episodes) is the least to base any kind of conclusion about his background, since you could have placed any policeman in his place and the story would have remained the same -- in other words, aside from the first three minutes, it was the most un-Columbo movie of them all.