Merging Acrobat 9 pro docs

[TheStump5333]

I'm using Acrobat 9 Pro.  I scanned in a book (with author's permission).  I messed up a couple of pages and re-scanned them and now they are separate documents.  How do I merge these pages into the master document?

[Test Screen Name]

Document > Replace pages or similar options in same place.

[JR Boulay]

In this case "Add pages" should be more useful than "Replace pages".