DealSheet is built to be used in Salesforce and allow for collaboration across the opportunity team.
If you think changes have happened in the plan, and you cannot recall making these changes, don't worry. All is not lost.
Use the "TIMELINE" menu item to view a log of changes to the plan, what was changed, who by and when.
You should be able to identify where the changes have taken place and then connect with the other person to discuss the changes.