Including groups in normal slicer

Hi everybody,

I am asking for help on an issue I can't solve by myself (been trying for two days...) :')

I am trying to display groups in a slicer without using the Hierarchical slicer. 

I have a list of countries (Portugal, Italy, Germany, France) and I made groups, which create the following table :

   Country      ;        Group 1           ;     Group 2

Portugal    ;    Southern Europe  ;  International

Italy           ;    Southern Europe  ;  International

Germany   ;    Germany               ;  International

France       ;    France                   ;  National

The column Country is filtering a big table with all the data.

I would like to be able to create a classical segment filter (and not a hierarchy filter, if you wonder why it is because my client finds it ugly and wants to add a search option...) which displays all groups and countries together in a list like that :

National

International

Southern Europe

Germany

France

Portugal

Italy

I tried to create a new tab with this list but I was unable to find the right relationship to make it filter the way I want, I also tried to create a table with the groups and the summed data corresponding and merge it with the existing table but it was a hell of a work and my DAX is not strong enough...but I will be happy to learn!

If you can think of a solution that would be a great help!

Of course if you need any more information I will give it to you don't hesitate to ask,

Thank you very much!

Best,

Léa