Nick I guess it really depends on how the payments are imported into your accounting software. If you're also developing that link by yourself, then you could just use the monetary account ID + payment ID (that will be the ID that is returned in the response body whenever you send a payment via the /payment endpoint).
However, if that's not the case, then maybe the accounting software is not aware of these payment IDs and can only look at certain attributes of the payment. So it really depends on that probably.
(You could also do some stuff like adding a note to the payment after you have sent it via the /note-text endpoint, but again, not sure if your accounting software can read these, and these I think actually cost money to use if you're using a business account.)