Dear Word community

In our company, we updated the corporate design (new Word templates with Styles).

Now a lot of the employees have reports (with 100+ pages) in the old design.

If they now want to update their old reports, is their only solution to copy and paste the text in the old documents and paste it (without formatting) into the new template and set the appropriate Style sheets, or is there a faster way? Combining the contents when copy-pasting it does not seem to work...

Does anyone have any ideas?

Thanks a lot!