ok . I understand now.. I was thinking about it the wrong way..
>Hi Matthew,
Thank you for your interest in Syncfusion products.
Using Essential DOcIO, we can create or modify the existing document. There is no need to recreate the whole document again. You can use your existing document and modify or append new content in it by using the find and replace or accessing the elements.
Please refer to our online documentation link to get more information:
http://help.syncfusion.com/ug_71/docio/default.html Please take a look into the documentation, still if this not helps, please let us know your exact requirement with your template document, it would be help us to provide a better solution.
Best Regards,
Bhuvana