Manual step 1. Prior to listing on the SM the loan is reviewed against the Secondary Market spreadsheet to ensure it is class "A" not impaired by a threat of early repayment or worse. Manual step 2 prior to completing the sale Admin check that no messages have ben received either moving the loans status or by the would be seller having misunderstood what they we doing.
I have 'A' level Physics but more relevantly qualified as an accountant. I'll admit that unless you grasp the nettle of working out how to obtain interest and capital by loan early in your involvement with Emaciated Moggies you are faced with a problem. If you export the Nominal Ledger to Excel and sorting use strip and mid it is possible to work out interest by loan etc.