The subassembly work tickets have a reference to the parent work ticket number, and on the parent work ticket there is a reference to the subassembly work ticket - ""Being made on . . . "" These references are only in the Work Tickets, but of course the initial 7 digits of the work ticket numbers are the sales order number.
The WTMadeOnOrder number is in the sales order detail table and so is the WTParent number. Those are at the end of that table (as ""JT158_"" fields), so you may be able to access those for the sales order.