Families & Friends of Gays & Lesbians Support Group
This community is dedicated to parents, siblings, grandparents, other relatives and friends of someone who is either gay, lesbian, bisexual, transgender or questioning their sexual orientation. The purpose of this community is to help families and friendships grow and maintain positive relationships with gay sons, daughters, family or friends.
As for her girlfriend spending the night, you say you'd know how to handle the situation if Z were a boy. Well for the sake of argument, imagine she is in this scenario. Your gd brought her boyfriend home and asked to spend the night unsupervised with him in the same bed. I'm guessing the answer would have been an emphatic "no". It is okay to set boundaries and not worry about them being disparaging to your gd's budding sexual and gender expression.
Another factor to consider is that Z's parents may not approve of her spending the night making out with her girlfriend in bed; regardless of the gender of their daughter's paramour. While I fully support you creative a safe space for these girls, don't let acceptance and compassion lead you to condone things you would have forbidden with an opposite sex sleepover. While Z may not feel comfortable in your GS's room, a couch will do just fine.
My job is to help my grandkids become functional adults. There is no girl book or boy book on what to like, what to wear or what to do for a living or what to do for fun. "Culture" makes the rules and cultures change all the time. So I want them to listen to what THEY want and we'll figure out how to get the "culture" to chill or just ignore em.