I recently had to do manual data edit for a client who mistakenly merged a handful of customers (...oops!), so I have a handy list of transaction tables I had to edit with customer number updates. (Your list may be bigger than mine):
AR_SalesTax, AR_InvoiceHistoryHeader, AR_OpenInvoice, AR_OpenInvoiceTaxSummary, AR_TransactionPaymentHistory, AR_CashReceiptsHistory, IM_ItemTransactionHistory, RA_CustomerInvoiceSearch, SO / history tables... and any summary tables based on sales data.