Events other than Games and Exhibition Games allow you to assign more than 2 teams. You can create a shared practice, or a shared training event etc.
Create a Multi-Team Event
Navigate to Events on the left
In the upper right click the Add/Import > Advanced Add Event
Select an event type other than game and exhibition game
In the Teams Dropdown you can now select more than 1 team
Once the event is created, this will appear in the schedule of each team that was assigned to the event