Bridesmaid Issue

I am hoping to get some feedback after having an issue balancing our wedding party. My fiance has 5 groomsmen and I have 4 bridesmaids that I am positive on having in my wedding. It would just be hard to pick another amongst my friends and family without upsetting someone. My cousin got married last year and used a fill in girl. I found out after the fact and she was great. Oddly she was a transwoman which was no big deal to us, we have a diverse friend and family group. The best part was she gave them a gift of $1000 and paid for her own dress. What are your thoughts on using her at my wedding?