@PedroPereira
So maybe you should use the view “Host group” from the “Monitor” menu and then set filters (substrings or regexes) for the groups you would like to see. Then you can add this filtered view to other dashboards.
Would this solve your problem?
Edit: just tried it and it works. If you remove the link from the title (which would make the view followable to the original unfiltered view) then users can only descend into the host groups they can see in the view.
Hope I understood your issue correctly 