add new fields on forecasting windows

Dear All, I have some problems relate to forecasting windows header. I would like to add this following fields into the header: 1. field a (code type) 2. field b (code type) 3. field c (code type) 4. Specific location type (MM, SM, GR) under costomer card (not location field) With the new fields above, I want the location can be connected to customer card, in the customer card there are no. 1,2,3 and 4 fields. in the forecast windows, If I selected one location, then field a that is related to location will automatically appear in its field, including field b, c and d. I have put all fields (4 fields above) in the item table and attached them into forecast windows header. But I don’t know how to do that. Any helps from you are really awaited, tks a lot beforehand. rgds, Mark