Begin with one currency and one case
Use the disputed amount as the case ceiling. Record the supplier and currency once, then tie every later credit to that same case. Do not apply one credit line to two open cases.
Require later evidence
A supplier email can promise an amount, but the verified amount needs a later invoice or credit-note line. Keep its original file and exact row or page. If the line is a reversal, record a reversing event instead of silently editing history.
Calculate the remaining balance
For a USD 54.00 disputed case with a USD 20.00 evidenced credit, show USD 20.00 verified and USD 34.00 outstanding. A later USD 10.00 credit makes verified USD 30.00 and outstanding USD 24.00. A promise does not change this arithmetic.
Export the timeline
A useful report shows the original calculation, each dated event, the credited source lines and the remaining value. It should also show any portion explicitly written off rather than treating it as recovered.
Verified credit describes source-backed records in this workflow. It is not proof of a cleared bank receipt or customer revenue.
See the partial-credit example