Sure, I coached (along with another parent) a girl's volleyball team, my daughter was on the team. I would not start a practice without at least 1 other parent there. And parents were always welcome to sit in during team meetings and practices. Always, always have a "team" meeting directly with parents before the first practice starts and explain the rules and boundaries. If the parents can't control themselves or let me coach as I see fit in terms of who plays, what position etc...they can request to move their kids to another team.