Last posting date in Bex

Hi all,

Below is my requirement,

there is a posting date in the cube, and while running in Bex we have to apply a logic to set the version (like actual,plan),

1. If key date (user variable ) <= latest posting date available for actual then set version = actual

2. If key date (user variable ) >  latest posting date available for actual then set version = actual and plan

Here the challenge is how to find out the latest posting date, I think this can be done via create a new info object based on virtual characteristic and derive logic to find the latest date,  but not sure how it affects while drill down to any characteristics. Any suggessions please?

thanks

Jose