Why are you not using EBELN for connecting these documents .
After all EKBE is PO history table and an EBELN's history is different MIGO and MIRO docs carried out with it.
Precisely field LFBNR of MSEG will give you the exact link between 122 Movement type document and its corresponding 101 document.
LFBNR for 122 Movment type Document will have the document number of corresponding 101 Movement type document as its value.