Beth,
I've written some reports based on history that pull the labor/materials; however, to accomplish this my client has to use either lot or serialized items, it was the only way I could trace back to the actual work order that created what is on hand. . From Memory I've accomplished this by linking the serial numbers of the items (found in IM_ItemCost) to the ""D"" records from WO9 table - D records are the serialized completion records this gets you the Work order number used for that completion. You Then link the work order number found in in WO9 to the work order number in WO1 table. The WO1 table then has fields for Actual Labor, Actual Material etc. This same basic concept would apply if you started with the invoice detail distribution tables.
I did this in crystal for a client that doesn't have a tremendous amount of activity. Later we had a client with huge data files so there, we pulled those tables into SQL and linked our crystal report to an SQL view that performed all the linking/sorting and selection of data to keep it running quickly.
if they don't user lot/serial, then I think it would be impossible to know what work order was used for the items sold or left in inventory.