One field with value from multiple measures that can be filtered by multiple filters

Question

I have the following calculated field:

{FIXED starttime, zone:
 max(if zone = zone b then 'calculated field  zone b'
elseif zone = zone c then 'calculated field zone c'
End)}

This calculated field allows me to filter on a specific or multiple zones and then shows the total for the selected zones that have a relationship with the calculated field as the if statement shows.

Now I have the same calculated field, but then for department:

{FIXED starttime, department:
 max(if department = department A then 'calculated field department A'
elseif department = department B then 'calculated field department B'
End)}

As you can imagine, both calculations are working with a different filter (dimension); department and zone.

But now I want to have 1 calculated field which contains the result of both calculations from above. So that when I filter on zone B and department A, I get the sum of the filtered dimension based on of course the underlying calculations which I talked about before.
This allows me to have one field to use in a sheet in stead of two.

How can this be achieved?

Thanks