A ghost sub is used when there is no real (human) sub available and you have one or more players absent. You can use the same ghost sub more than once in an event. You can also name the substitutes. For instance, your league may have different scenarios for when one member of a team is absent and another scenario for when the entire team is absent. You can use different ghost names to describe the scenario.
This video shows how to limit the total points a ghost substitute can win.