Are you asking how to insert a complete text file into a specific location in a document?
Or are you asking how to parse a text file to find a specific item to bring it into a defined location in the document.

If it was me, I would start by 'tagging' the target locations in the Word document by inserting Content Controls and either map them to embedded XML fields or use their Title and/or Tag properties to populate them from the text file inputs.

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Andrew Lockton
Chrysalis Design, Melbourne Australia