Hi Viral,
You can follow what Kalyan said but that approach may cause issues with some users whose context are not set properly. What would I do as a work around is as below.
Lets say Cell A2 has EPM Context formula like EPMContextmember(,"REGION")
IN a hidden cell I would use another EPM formula to retrieve ID' for the selection in cell A2 irrespective of whether A2 has only ID's or ID and Description.
for e.g In Cell A1 I would use =EPMMemberProperty(,A2,"ID")
Now I would use Cell A1 in my EPMDimension Override formula instead of A2 directly(context selection)
Hope It helps !!
Regards
Nikhil