I think that totally depends on your daughter. She is the one who gets to make these types of decisions. She may not be comfortable with the idea, she may worry how that may make her mom feel, she may just not want you to be....OR, she might think it's a wonderful idea...fair or not, its up to her. Kwim?
My mom placed my sister for adoption (my aunt adopted her) My mom is definitely not "grandma" to her son. In no way shape or form. I don't think it's something that should be assumed.
But ya know, I'm Aunty...lol
It all has to do with our relationships and our comfort levels...and to an extent realizing our boundaries and roles..make sense?