Technically no, it is not possible to modify a revision if it has been published. But we do have a workaround you can follow:
- With your manual open, go to Settings and select Revision Archive
2. Make the revision not available under Revision Settings. This way the revision will not be visible to the readers or in the revision summary
3. Click on Save
4. Create a new revision with the same name/number, set the new revision to track changes from the desired revision
5. Edit pages and publish again.
Note: To reflect new revision number, page(s) have to be drafted.