Number of groomsmen

Hi all, especially 2023 brides! Happy New Year! I’m definitely a bride who doesn’t mind going against tradition and doing things our own way, but I could do with some opinions on this topic as it’s one of the only things myself and my partner are disagreeing on. My partner has 5 groomsmen (his best friends) and wants them to all wear matching suits, which will be just plain black suits in line with our monochrome theme. I have suggested that I would like my Dad and 3 older brothers to also wear the same black suits. That would mean there would be 10 of them in black suits. The issue is, we are only having 60 day guests so that would mean that one sixth of the day guests would be matching. I don’t think that’s that bad but he seems to think it’s a lot! I really want my brothers to feel involved as I am their only sister. Thoughts…?