Add field to many-to-many relationship

Question

I have a relationship between the Cases module and a custom module. It's a Many-to-Many relationship. 
 Is there a way to add a new field to that relationship? I couldn't find a way in Studio.

Arty Simon · Accepted Answer

Relationships do not have fields, so to achieve this outcome is to create a "junction" style module. 
 For example, lets say you have a custom module (Events) and your core module (Contacts). You want to be able to say that many people attend many events and track some information about that relationship (e.g. are they invited / attending etc). 
 Instead of creating a m:m relationship between the two modules, create a new custom module "Event Registrations", with a 1:m relationship each way, i.e. one Event has many Event Registrations and one Contact has many Event Registrations. Then at the Event Registration level, you add the fields - e.g. status, dietary needs and anything else which you would have otherwise considered a field of the 'relationship'. 
 You should be apply this same approach to your implementation with your Cases module and the custom module.