League TBA Games
You can schedule “League TBA” games which allow you to use placeholder labels for games without creating dummy teams.
In the scheduling module go to Current Season -> (choose a league). The Add New… dropdown will have a “League TBA Game” as an option when viewing things at the league level.
Those games allow umpires to be assigned before knowing what teams will be in them, and can be converted to local games while retaining the umpires (if assigned). A league TBA game, since any team in that league could be in it, shows on all team calendars within the league – so just use the labels of the TBA game to accurately describe which teams could end up in those spots and that will make it clear for everyone.
There’s also a way to bulk convert league TBA games in cases where you have a bunch of them and the same labels are in place for all of them.