[cflsystems]

The ideal workflow for XC 4.4.x and up (I think not saving anon customers started with 4.4.x)

1. Use the default XC search for orders to search based on customer data - since there is no customer you cannot search users.
2. Found some orders - mark the orders (just like marking them for deletion) and there should be a button on the page - assign these orders to customer.
3. Next to the button can be a dropdown list of all registered customer to select from so click on button and the script will assign the orders to that customer based on customer id...

Of course customer has to be created first

Not that hard to do. There could be a little bit more than just adding userid to orders table though but as Carry mentioned it is easy enough to be free mod