How do i include my underage bridesmaid in the bachelorette?

Hi, I'm Viviana and I have a bridesmaid, my niece Ava, she's 12 years old. I don't really like calling her a junior bridesmaid because she feels like more than that to me, so I am just going to say bridesmaid. She really loves this role in my wedding, she's great with planning and is overall a really good bridesmaid. I don't really want to have an inappropriate bachelorette and I also want her to be able to join the fun, so I need some ideas on a fun, PG bachelorette idea. I was thinking maybe a movie night with popcorn and chick flicks or a day at a local spa.