P31113 - Wo Inv Issue want ot pick BU from F0006 BU and not the Parent BU

WO Inv Issues- P31113 it looks at AAI 4124 where BU is set to blank and it only has the Obj and Sub. For now it picks the BU from BU Mst Project# (Parent BU) . Is there a way to pick this up from BU itself and not the parent BU. Please advise. I was thinking if we could use Flex Accounting.