Download Excel as a mail merge in a Word template and display the Word template with all the fields, but using the C # code

I have uploaded a photo. I want to download an Excel file as a mail merge inside a Word template, but with the help of a C # code. There are many mail merge methods. But manually, we upload an Excel file into a word template to merge the values ​​( Check out this youtube link for a better understanding, please. But I want this Excel file download in a word template to use the form code c # win only. I really need your help for that, please. Specify the path only by uploading an Excel file into a word template, because I know all the other methods of merging. I want to download an Excel file inside a Word template with the help of C # code, please. Thank you
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