This might be easiest done by linking a text file.
By default, text you place in InDesign is not linked to the original
text file. However, if you select the Create Links When Placing Text
And Spreadsheet Files option in File Handling preferences before you
place a file, the name of the text file appears in the Links panel.
You can use the Links panel to update and manage the file. When you
update a linked text file, any editing or formatting changes applied
within InDesign are lost. Because of this risk, linked text files are
not automatically updated when the original file is edited. However,
you can easily use the Links panel to update content or to unlink
(embed) the file.
Do one of the following: To apply this change to a document, open the
To apply this change to any new document you create, close all
Choose Edit > Preferences > File Handling (Windows) or InDesign >
Preferences > File Handling (Mac OS). To create links in placed files,
select Create Links When Placing Text And Spreadsheet Files. If this
option is turned on, use the Links panel to update, relink, or remove
links. If this option is turned off, text files are embedded (not