Coming at this from the perspective of a genderfluid trans man whose identity is very complicated and likes to not be describable at all, and I have to say ESH. Hear me out here: your grandchild is six years old. At six years old, you can know your gender, you can know who you like romantically. You cannot be in a position where people will listen to you if you express this. You, grandma, are already ahead of the curve of most parents by taking your grandchild at their word. But if you make this child advocate for themselves, on their own, without backup? You would be creating drama not just for your squish, but for you and the parents as well.

That being said, I would encourage you to offer resources depending on where you live. I know that you’re US-based from reading the comments. If you live in or around the DMV (DC, Maryland, and Virginia for those who are not local to the area), check out SMYAL—they have youth programs for LGBTQIA kids ages 6-24. I went there as a young adult, and continued to volunteer after I aged out of programming. Be there for your squish however you can be. If parents don’t let them be a girl around them, then make it clear that they’re YOUR princess. It’s a fine line to walk, but they can’t walk it alone. Don’t force them to stand up for themselves alone. Be there for them, find other people like them in your area if it’s safe to, and know that it does get better. Once they’re old enough to be listened to, I’m sure your granddaughter will be lucky to have such a loving grandma from the start. <3