[Opinions] yes, it's quite a stretch ...
And it's actually kind of pathetic and embarrassing. I mean, cut out the fact that Poppy is an actual name and you are essentially naming the kid Grandpa or Grandaddy.
Mila for Margaret Laura isn't quite so bad; at least Margaret and Laura and Mila are all actual names. But if you wanted to go that route, Marla would make more sense as a nn, and could have been a resonable first name to commemorate both grandmas.
Before you criticize a man, walk a mile in his shoes. That way, when you criticize him, you're a mile away and you have his shoes!
Steve Martin