How to filter 'child' entity in VBCS add-in

Hi. We want to use VBCS to manage master item data and item category assignments. So we use Items v2 REST service, and it works fine but the point is that we want the system to download only the item category assignments for a specific catalog called MINMAX. How should we define the query parameters for this entity to get this filter? We would appreciate to be specific about what and where to enter...

Thanks a lot