To do this, please follow the below instructions carefully:

1. Open each chapter document and in the EndNote tab of each, click on 'Convert Citations and Bibliography' > 'Convert to Unformatted Citations'.
2. Copy and paste your documents together into one final document.
3. Ensuring that your corresponding EndNote library or libraries are open, in this final document click on 'Update Citations and Bibliography'.

Your document will be reformatted in your chosen style and will display one final bibliography at the end.