How to create a Column for net Due date, Due date for cash discount 1

Hi everyone,

my Finance Department want to have Customer Line Item Cube,

In the Cube, there are already Columns: Due date, Due date for cash discount 1, and now they want to have a column in the cube like this:

On line Item level:

- If the due date for cash discount 1 is not passed, then only due date for cash discount 1 will be shown

- If the due date for cash discount 1 is passed, then only net due date will be shown

- If the net due date is passed, then the current date will be shown.

Can you please help me how to create this Column?

Because im not familiar with Bex, and its not Standard report form BW.

Thank you very much!