MIL wants to be called....

FutureMrsTowns

Deeva....(pronounced Diva)

this seems very weird to me, and I really don't want to call her that. We don't have a great relationship and actually JUST started talking for more than 5 minutes at a time. I'm very passive so I can't even bring myself to really argue with her. I mentioned that I think it's silly and I said I don't know how I feel about that, and she laughed and was like "you don't have to call me that" but she wants my kids to call her it. I kind of feel like SOME version of the word grandmother would be more appropriate, she's not a teenager anymore, but I don't really know how to say it to her. any suggestions? should I just let her have her way? (there's a part of me that probably is fighting this just because it's her idea, since if she weren't DH's mom she'd have NOTHING to do with LO)