Thanks Ryan.
I thought there would be already a field doing that in the ItemReceiptLineItem table, and there is a field called "LinkToPurchaseOrder" which does that. However, as I mentioned in one of my previous post, that field will be emptied as soon as that ItemReceipt has been saved. When I just select the PO, and before I save the ItemReceipt, it has a valid value.
I could add another field to link the right PO number, but the problem is that if somebody else does an Item Receipt in QuickBooks, then whatever field I added into the ItemReceiptLineItem table would not be updated. I do remember the QB SDK does give us the PO Txn number when doing a Item Receipt, I just do not know why Method does not keep that inforamtion for later use.
No matter what solution I use, it has to work both with Method and QuickBooks alone, since one of our people will be still using QuickBooks.
So if you think of anything, please let me know. Thanks