In QuickBooks Desktop, you can merge two separate customers. Here's how to do it: Select Edit Customer from the context menu when you right-click the name of the customer you want to merge. Select OK after replacing the client name with the one you wrote down or copied. At any given time, you can only merge two customer records. If a client has three or more records, you must merge the combined record with the final customer record by combining two of the records and repeating the process. To know more visit here: How To Merge Customers In Quickbooks?