Alternate state inside measure

[aheavy95]

Hi all,

In a Dynamic table (Ad hoc reporting) I've created -

the user selects a store (green mark) , dimensions a measure (black)

And as a result-  only stores that have the same values as the store selected (green)  in these dimensions (FC, TENBIS in this case) , are shown in the table. (implemented with alternate states)

In one of my dimensions- Area, instead of showing restaurants with the exact number only, I want to show the ones that are in the range(of +-20) of the selected store's area. 

This is how the dimension field is implemented  (same for all). What should I add in order to achieve this? 

=Aggr( Only( {StoreComp1} BrutoArea), BrutoArea)

{StoreComp1} is the reference to the alternative state 

 Thanks