Parents sign in to plan meals and edit recipes. Kids don't need to sign in.
To change every one of them (the time, the name, or stop it repeating), make the change in Google Calendar instead.
Pick your name. This phone remembers it, so each person gets one vote per meal.
Kids don't need an account: just send them the app link. Use this to make someone a parent who can plan meals and edit recipes, like your spouse.