I'm proposing having a sandbox version of the manifest and a final version.
This would be toggled on and off with a checkbox in the item view.
If sandbox is checked on, changes to the manifest would be saved to sandbox.
If sandbox is checked off, changes to the manifest would be saved to final.
If you click on sandbox check box the manifest would revert to the last saved manifest in sandbox mode.
If sandbox check box is clicked off then the item view would revert to the last saved final version.