Store extra data to a Post/Taxonomy relationship?

Does anyone know how to store extra data to a Post/Taxonomy relationship in WordPress?

I have a post type “game”, and a taxonomy “leagues”, and I need a way to assign some extra information on the relationship.

If anyone has used Laravel before, it’s just like the second example under “Working With Pivot Tables”: http://laravel.com/docs/5.0/eloquent#working-with-pivot-tables

I basically need to store 1 boolean field which stores if the game is the “primary” game in that league.. It has to be done on the relationship as a game can exist in multiple leagues and they may not be “primary” in both.

Any help is greatly appreciated, however small. Thanks in advance 🙂