Dynamic Rolling flag selection

[SASUserRocks]

In SAS VA , i want to have a drop down for Rolling like ' 1 month','3 month'

If 3 month is selected, my NPS data must show a sub total of scores for current month ( which is a parameter in date mmm. format) , current month -1 and current month -2. The result needs to be there in List table.

Input data :- 

Month         NPS

Jan               10000

Feb                20000

Mar                30000

Here period is in button bar and selection of month is stored in parameter. 

rolling input :-

3 months

6 months

If i selected Mar from first source and selected 3 months from rolling source , the output should be as below.

Mar 60000

How to achieve this in SAS VA

[SASUserRocks]

Here selection of 3 months is taken from a dummy table. Kindly assist to resolve this.

[SASUserRocks]

In SAS VA , i want to have a drop down for Rolling like ' 1 month','3 month'

If 3 month is selected, my NPS data must show a sub total of scores for current month ( which is a parameter in date mmm. format) , current month -1 and current month -2. The result needs to be there in List table.

Input data :- 

Month         NPS

Jan               10000

Feb                20000

Mar                30000

Here period is in button bar and selection of month is stored in parameter. 

rolling input :-

3 months

6 months

If i selected Mar from first source and selected 3 months from rolling source , the output should be as below.

Mar 60000

How to achieve this in SAS VA