How to embed an iframe into a Word document?

We can use VSTO document level project to develop such a customized Word document. Word document level solution provide the function that let us add windows form control on surface of a Word document or Excel workbook. Consequently we can use a WebBrowser control to achieve what you want.
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https://social.msdn.microsoft.com/Forums/office/en-US/e981fe5c-4c59-4b6f-9076-c7ea90909616/embedding-an-iframe-into-a-word-document
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