By default when you create a groupstage each participant plays each other once. But you can easily create the home and away matches in Toornament.
You will find the home and away option in the structure section. Select your groups, go to the configuration and the structure tab. You will find the pairing method. Select double robin, it will generate home and away matches
More than words, watch this video to see how to create your home and away matches:
One tricky part about the Round-Robin Groups and League formats is the tie situation, where two or more participants end with the same amount of points.
That’s why Toornament handle Tiebreakers, to rule the final standings.
All events must comply to a mimimum legal framwork, depending on the country and laws. But in this field, things are never simple.
Here are some basic but useful advices, before you dive into it with legal experts and lawyers.