I would also like to add this:
Gmom doesn't respect Mom's rights or feelings at all. Who's to say she'll respect those of her Gkids? I'm not crying abuse, but I can easily imagine Gmom telling Gkid "I don't care if you want carrots, you're getting peas because I say so!"
Combine that with seeing Gmom disrespect Mom, and the Gkids are going to grow up thinking that love = subjugating yourself to the dominant person's wants and needs.