Best way to clear negative stock at subcon vendor

Hello Experts,

Good day.

Would want to seek your advise on this issue.

We have a subcon PO and user incorrectly update the component qty making the backflushed qty. greater than what was sent out to vendor. Due to this we now have negative qty at subcon vendor. PO is already GRed and IRed. What would be the best way to correct this? We cannot use MB1C to manually add stock in Production.

Appreciate your advise. Thank you!