(not meant to be rude or dismissive, just a joke)
Anonymous wrote:I don't think Mr. FirstName is rude, and would likely pick that; but since you do, I'd go with Grandpa FirstName. It is common among many grandparents, so it won't be unusual or offensive, and it will be easy to keep up that trend if she keeps getting remarried.
IMO, rude would be GrandpaSix

Anonymous wrote:Steve. I feel like they are usually named Steve