Sharing changes to a post (preview changes) with another user

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Don’t know of a plugin but a good approach would be:

  1. to crate a custom post type (shared_revisions).
  2. add a metabox to post edit screen which will have an option to save the post changes
    as a sheared_revision and store the original post id as postmeta of the sheared_revision post.

  3. add a metabox to your sheared_revision edit screen which will have
    an option to overwrite the original post.

    Hope this make sense.