In order to get MS Word to allow adding of merge fields, the template needs to be linked to a datasource. I assume that means you need to set the datasource in word to the xml file. Is this correct? Because when I try to do this word tells me “This file has custom XML elements that are no longer supported in word. Saving this file will remove the elements permanently” and it still does not seem to work correctly.
Is it possible to download the template file from this example? I can find links for the source code but not the actual docx template file.
Thanks for your feedback. It is good to know that you found the required information.
In reference to your query about the difference in Simple Mail Merge and Mail Merge with regions. Please check following documentation links these will help you to understand the difference between both types of Mail Merge.