Change FF logic to refund PTD amount instead of YTD

Hi Team,

I have a ESPP contribution FF attached to element which is currently refunding the whole YTD balance if the assignment's status turns to Inactive. My requirement is if the person is terminated post 07/01 (MM/DD) the refund aount should be calculated on basis of PTD DBI logic such as: number of periods *(Periods paid post 7/1) and not refund the whole YTD contribution he made stating from 1/1 to 6/30. Please help in putting up that logic .

Thanks.