Is there a way of keeping track of content copied from a Word document into a RTB on a VB Form?

I am creating an application where the user clicks on a Command Button which then populates a RTB with the content from the MS Word document.

I need the user to then be able to highlight a section of text within the RTB, click a 'Covert Text to Heading1' button and then see the same text within the Word document converted to the Heading1 style.

I have been trying for ages to get something going, but am having difficulty relating what is selected in the RTB to the same text in the Word document.

Any ideas would be much appreciated

Thanks,

Chris