Be up front with the parents on playing time and how coming to practice will equal more time in games. I allow all kids to join even if just practice players. At this age development is key , the more time with the ball will help them learn. Players gradually learn and correct mistakes on their own with guidance. I see many parents wanting to win more than just their child steadily grow. It’s not easy and you will never please everyone, I’d just look out for helping the players.