Dear Natalie,
I just wanted to introduce myself to you and set the ground rules for our new relationship. You may only be a month old, but I figure it’s never too early to get things off on the right foot.
First off, I am your Grandpaw. I have staked out that name. It’s mine.
You can call your other grandfather whatever you like except Grandpaw. I have a few suggestions, such as Gramps, Grandad, Granddaddy, grand pappy, Granpop or Bobo.
But remember, I am your one and only Grandpaw.