When editing a general journal entry, the Linked Record field requires a value for the line item along with the A/R account. What needs to be entered here?
You can post an A/R adjustment against an overhead project as the linked record and also confirm the A/R account to balance it against. We do recommend making a separate entry instead of editing an existing one. In case you need to find that entry in the future, it will be better to keep it separate. You should also add a memo there to explain why that entry exists.