Row Level Security and Slicer

Hello Experts,

I am stuck with one problem and need your guidance.

I have a table and it has 4 departemnts like 10,20,30 and 40. I have set the RLS with each departments respective managers so when dept 10 logs in then he could see just his data, for dept 20 manager, he can see just dept 20 data and so on.

Now these departments want to share the data amonst then e.g. say dept 40 is sharing his data with dept 10. So I have created one column in table like 'shareddata' and put value 40 against dept 10 records. Then I have created a slicer in PBI with shareddata values.

So when dept 10 manager logs in then he can see dept 40 in this slicer but he also want to access dept 40 values when he clicks on this slicer. But, I guess, due to RLS he can just see dept 10 since his role is set so.

When I just select values in this sclicer then the visual shows respective values but when I run "View as a role" for dept 10, it just show dept 10 values evenif I select dept 40 in the sclicer.

Could anyone advise how to achieve this type of functionality? 

Please help!