What you are looking to do is “add a guardian”. Please limit this feature to actual guardians of your child. Do NOT use this feature as a way of sharing your child’s game schedule. Guardian’s interact with the team, RSVP to games, and perform other functions.
If you do want to add a guardian, this is done by the person who registered the player. You don’t have to trouble your coach with this task. Instructions on adding a guardian for a player can be found at https://mobile-help.sportsengine.com/en/articles/9-how-to-add-a-guardian