Instead of the Mail Merge Wizard, you can use the Mail Merge Toolbar schematic. That is turned on by the View menu | Toolbars | Mail Merge.
The First button is the Main document setup. You can see a tooltip describing it when you hover your mouse over it.
The next button - Open Data Source - is the avenue for selecting your Excel spreadsheet.
Your data source can be an Excel spreadsheet or a Merge File made in the Reporter.
The next button - Mail Merge Recipients - lets you confirm all the addressees.
Insert Address Block
Skip the Insert Greeting step when you are doing envelopes.
Insert Merge Fields
Put the dot next to Database Fields.
When you get the Invalid Merge Field screen you can add and remove fields.
From here you can Print from the File Menu and change printers.