When preparing templates of any type in the document editor, fields can be declared merge fields by selecting "Filled By Me (Before Sending)" from the top "Filled By ..." menu, which appears when an eligible field is selected.
When preparing templates of any type in the document editor, fields can be declared merge fields by selecting "Filled By Me (Before Sending)" from the top "Filled By ..." menu, which appears when an eligible field is selected.