Players in the teams can be added at any time, no matter if the team league has started.
Players in a team can be added from the team manager. To open a team manager, go to the team league page and open the “Teams” section. From the teams section select the team you need to add players to. Click on the team name and you will be redirected to the team page.
In the team page, click the “Go to team manager” button.
In the team manager, you can search for the players and add them to the team.
After selecting the players, click the save button at the bottom of the page.