Unflatten Annotations
If the "Allow Unflattening" option was chosen when Flattening Annotations you can then unflatten the annotations at a later time.
NOTE: Any additional document or content changes performed on any page could affect unflattening so it is recommended as a final step before saving the document.
How to Unflatten Annotations:
From the Comments Tab choose 
Flatten drop down -> Unflatten Comments
Options
Pages - The range of pages to be exported as images
- All Pages: all pages in the document
- Page Range: set the pages to be exported using the From and To options
- Even Pages Only: only export the even pages of the document
- Odd Pages Only: only export the odd pages of the document