There doesn't appear to be any way to add any notes to an outstanding receivables invoice to record when and how collections were attempted, any other relevant details etc. When we do repairs that will be covered by a third party warranty, the invoice may be in the name of our customer, but we're expecting payment from the warranty company. Sometimes you have to speak to multiple people/departments, to follow up on the payment portion, and having a place to record those specific details would be very helpful.