We kind of tossed these around, as my mom had been "Grandma {{name}}" for quite some time before I ad a kid, and I wasn't going to make her switch. My MiL, though, we wanted to give her the honor of "Abuela," which mean FiL would have to be "Abuelo," a name that he has no connection to. Fortunately, "Abuelo" rather enjoyed being called that.