As long as the event you're attending has created and enabled the guest player pool, coaches and managers can add any registered guest players to their teams with these steps:
1. Log in to your account, click on team management, and select the desired team to add a guest player.
2. Click on Team Registrations and select the event you would like to add a guest player for.
3. Select Athlete Pool
4. You can search guest players by user name or email. When you find the desired player, click assign player.
5. Enter the player's jersey number and click add player