Country Filter with (many-to-many) type of association

Hi guys, I've got a list of lawyers that I want to be able to filter by operating countries. I've already have them filtered by Law Firms as you can see in the image. 1 "Law Firm" object is associated with multiple "Lawyer" objects and, (one to many) * "Country" objects are associated with multiple "Law Firm" objects. (many to many) I have tried using a filter like the one in the image, but it's not possible due to the (many to many) type of association. Other filters that "do" work conflict with other elements on the page (header widgets, listviews, etc). So I was thinking about using a button and a microflow for this work, so the rest of the page would continue working just as fine. Do you have any suggestions that would make the development of this feature more feasible? Thank you,  
1 answers

Personally I never like *-* associations. Usually you can make a new entity between them (most likely called: CountryLawyer entity).