Custom fields in relationship tables in module Report


I have created a relationship by studio between AOS_PRODUCTS (Im using for Courses) and Contacts. Then, I created three fields in this relationship table special_price, type of contact course(user or curstomer) and user of sales

I want to make a report to get only user (type of contact course) who are registered in a particular course (aos_product)

My question is how can I add this fields in a report module to put as filter or field in report

This is the same logic as delegates modules, I have created fields in delegates tables ( fp_events_contacts, fp_events_leads, fp_events_prospect)
I cant find this relationship fileds in report module

If is not implemented how can I implement this?

Thanks in advance

Martin Contreras