I think you've cracked it! ;)
Sub report 1 = SalesQuotationItem
Sub report 2 =QSalesQuotationItemAcc
Sub report 3 =SalesQuotationItem2
In report 1, Form filter ...
IIF(DCount("*","QSalesQuotationItemAcc","OrderID = " & OrderID)=0,POSITION>0,POSITION <...