You don't. You're putting your fiance in the position of choosing her daughter or her boyfriend, and that's not going to end well for one of those teams. And based on your post, she's going to side with team daughter.

And her daughter doesn't think of you as a father. To her, you're just her mom's boyfriend.

If you go ahead with it anyway, just be blunt about it.

My parents and extended family went like with the raised rent plan: Bring up the possibility of rent or bills, since she's an adult with a job and not a child anymore.

"I'm tired of (GFDaughter) living here. I'm tired of being disrespected and outright hated in my own home. She's an adult, she has a stable job, and she needs to start paying rent or finding a place."

But at the end of the day, it sounds like she's going to side with her daughter over you, so I wouldn't expect much.