I'v been thinking of this all evening and frankly I'm wondering why she feels she needs us to give her good reasons to use.
If she has concerns she should address them to her ex.
Who are we to know if there are more serious issues behind her reluctance to willingly let her daughter go. Obviously the GGM is a paternal one.
If I could I'd delete my previous comments so Mom could deal with it on her own.
I don't know her or any of the parties involved., so I have no way of honestly having an opinion.
Sorry.