CubeView dynamic Calc

Hello Experts

i'm trying to create a report to calculate fcst numbers based on driver.  for driver, i'm using dynamic calc where i'm taking 3 month moving avg as %. my user wants the ability to tweak %. how can i do that? if i add an additional column and ask my user to just enter change in %, i can add both columns using cvc. but the accounts in my rows are parent members. i cant save data at parent and i do not want to use text properties for accounts.