Filter with multiple columns

[reshmars]

I have 3 columns

which should come in a single filter dropdown . But the condition is such that if it is enable then all countries should be listed for value 'E' . If flag is selected then, the 2 countries should be listed  as  'Live' else 'NA' . The code is as below. 

sql: case when ${enable} = 'E' then 'E'  when ${flag} = 'Y' then 'Live' else 'NA' end;;

The issue is , for example, if enable is selected then flag condition won't be checked and if flag is written first then, enable condition which has flag also as 'Y'  won't be checked. The flag is a subset of enable.- i.e., all countries with flag 'Y' are by default 'Enable'. So , I need all countries with flag as 'Y' to be listed in enable. How to do this in looker.