This doesn't make sense. Sorry but why is your friend making demands on who should attend get togethers on the guy's family gatherings. The fact that the guy has agreed is a big red flag. Tell yes to everything now, and once married, he can say that its their life and he can't control whom they wish to have during their get togethers. Either your friend should accept everything and get into wedlock or walk away. If you are putting conditions, you are setting yourself up for disappointments later.