My Mum has always been Nan, and my Dad in no way wanted to be Grandad or anything similar, (made him feel too old), so he went with Papi. He got the idea from a Spanish family we'd become friends with on family holidays and it's stuck, 4 Grandkids later, (not all mine!), and he's still Papi and it definitely suits him.
Not sure I'll be Papi when the time comes, but then again don't want to be Grandad either.
Hearty congrats to you and yours
