You could try to use smart fields, smart relationships and/or smart collections. These three features help you design your collections, your relationships and your fields the way you want, so I guess it could help you in building this unique view (a kind of a collection that aggregates two collections). My bet would be to try to build a smart collection for your actual need, still, it’s an advanced feature, so you would need to be familiar with Forest Admin concepts.
I let you discover these concepts through the documentation, feel free to send me feedback if you face any problem or if you have any question.