I already have a regular shinny crew. Can I fill in part of the roster myself if they're not yet on HC?

Yes, there's a workaround to do this on HC! This workaround will create them an HC account and send them an email with the account details and a temporary password. 

1. In the sidebar, under ‘My Teams’, click the Create a Team button.
   
   
2. Fill out your team name and type of hockey would be ‘Ice Hockey’. Click Create. 
   
   
3. Under Schedule, hit the blue button to create an event. Change the event type to ‘Drop-in/Shinny/Pick-up’ and make sure to toggle on ‘This event is public’. Make it a recurring event like you did previously.
   
   
4. Navigate to the ‘Roster’ tab, then hit the blue button to add players. 
   
   
5. Enter the player’s name, email address, and position/jersey number (if applicable). You can also set their roster status to Full time or Spare. Full time will automatically be invited to all events you create in the future, whereas Spares have to be invited to the game. [Note: if they’re already on HC, you can just select them by searching for them in the ‘Name’ field and selecting them from the dropdown list]
   
   
6. If they are a regular, you can toggle on ‘Automatically Signed In For Each Game’. 
   
   
7. Click Add Another until you’ve finished all your regular players. Once you’re done, hit Add Player to close the dialog box.
   
   
8. All players should now be added to every game you created.