You can always add players, but we can't change the split number.
You can add players up to your roster maximum (varies by sport). You can request a player removal by emailing firstname.lastname@example.org as long as you have at least 2 games remaining.
If you split the team fee, once you complete the team registration, that number cannot be changed. Any additional players will be able to register without paying the team fee, and if you fail to meet that number, any unpaid team fees will be reassigned back to you the Tuesday after registration closes.