Replace a player in a single match
To change one player or team in a match that's already on the schedule, tap the pencil icon next to their name on the match card and pick the replacement. The rest of the schedule stays as it is. This works in Round Robin (Set Partners), Rotating Partner Round Robin, Ladder League and the other ladder formats, brackets, and Team Events (MLP) matchups.
Replace the player
Only hosts and club admins see the pencil.
If the replacement isn't in the event yet, add them on the Players tab first.
On the Matches tab, find the match and tap the pencil icon next to the side you want to change.
If that side has two players, pick the player who is out.
Pick the replacement from the list.
Confirm. In round robin and ladder matches, the button reads Replace Player or Replace Team.
In Ladder League and the other ladder formats, the list shows only players (or teams) on the same court and those who aren't playing that round. To move someone between courts, use Edit Groups.
In round robin matches, you can choose Swap instead of Replace. The two players or teams trade places, so the other match changes too.
Set partners first in fixed-partner formats
In Round Robin (Set Partners), Ladder League (Set Partners), Up and Down the River (Set Partners) and doubles brackets, the team is what plays. Before you change the match, edit the substitute on the Players tab and set their Partner to the player who is staying. Otherwise the new pairing won't be in the list.
In a bracket, a change to one match carries into later rounds through whoever advances. Check the next round after you change it.
When to use something else
For a sub who covers whole weeks of a league, register them from the Players tab instead so you control whether their rounds count in the standings. See Keep a sub pool and choose how subs affect standings.
When the change should reshape every upcoming round, see Make substitutions across event formats.