Grandma being called what?

So hubs and I both called both sets of grandparents grandma and grandpa growing up - not a different name for one set.  My MIL threw me this amazing shower yesterday and in the cards from her gifts she signed them from Nonnie and Pa. My hubs wants baby to call them grandma and grandpa like I want my parents to be called grandma and grandpa - and if baby calls them something else we can try to go with that :) but what do you do in this type of situation when the other grandma and grandpa have staked claim on Nonnie and Pa? I grew up in the country and Pa is a term for Dad and I don't know what a Nonnie is, actually.  My MIL made a big deal about what my grandma would be called and I said "great grandma, just like my great grandma was called" she didn't like that either...anyway, just looking for some helpful insights on what you would do and if you have been in this situation before (second time moms) what happened with both sets of grandparents? Thanks for your help :) I appreciate all positive comments :)