Sorry for the misunderstanding. The importing of headers and footers is again a concept that is not the same as in DOCX and RTF documents and it is a rather custom solution to handle such a situation.
You can manipulate the imported content via the server-side OnImportContent
event. Although, you should firstly decide how the headers and footers should look like in an HTML document and alter the RadFlowDocument as per to the needed requirements. Note that in HTML, there is no concept of pages, into which to show header or footer.
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