My dad’s dad got re-married after grandma died, too. We rarely call the “new wife” “grandma” even tho she’s been around since we were under 10, and we love her to bits. We still call her by her first name.
The funny thing is that she (new grandma) has this brother who is a pretty weird dude. He’s always hanging around their house - my grandpa hates it. He complains about him to my dad and my dad complains about him to me.
I recently pointed out to my dad that this dude is technically his uncle, by marriage. Totally threw dad for a loop!
(sorry to hijack. carry on.)