PO information for current onhand quantity

Hi,

We have a requirement from one of our customer to get po information for current onhand quantity.

We have tried to get po information from mtl_onhand_quantities table.

But the create_transaction_id and update_transaction_id is updating automatically when user performed sub inventory transfer and it is difficult to get po information for such transactions.

Please help us how to get po information for such transaction  from backend tables.

Thanks

Rama Devi