How to add a coach to a team, use the "Teams" menu on the right, then find the team and edit the staff for the team:

https://youtu.be/mv2nh6a1byw

If the parent has NOT coached before, an admin must invite them to be "Staff" in the club before they can be assigned to a team.
Use the "Staff" Menu on the left, then the "Add Coach" button at the top right.

https://youtu.be/5-LFLnYRuVw