Sales invoice does not allow negative quantity

We have concession items that need to be processed into Sales Order and Sales Invoice. Returns are reflected as having a negative quantity. I am able to submit in Sales Order but i get the an error in Sales Invoice. How do i go about this issue?

Why don’t you handle concessions using discounts?

Yes we are already using discounts. We base on concessionaire’s report of sold and returned items. Entered it in Sales Order and proceed to Sales Invoice where discount is applied after which payment entry is made so that the report is booked as paid. With the latest update v10.1.13. We are not able to submit Sales Invoice having a negative qty to handle returned items in the report.

did you find a solution for negative quantity?
We just updated from v10 to v11 and ran into the same problem.

Seems like this check was introduced with: