Hello Neil,
When you change the Payee of one of the downloaded banking transaction, QuickBooks will automatically update others to the same Payee. We can create a bank rule so we can categorize your transactions properly. You can use this article for more information: How to Set and Use Banking Rules for Downloaded Transactions.
Meanwhile, you can directly add the downloaded banking transaction to your register even if you don't assign a Payee. You only add the payee if you want to associate the banking transaction to a specific entity. It would also help you categorise your transactions well.
If you're referring to something else, additional details would be much appreciated.