Tempo Ideas

is there a possibility to view the history of a time plan?
Reason: a user can submit his plan for approval. If it got approved he is still able to change it. After changing it it is not approved anymore (as expected). He sends again for approval. Is there a possibility for the approver to see how the plan was before?

Or is there a possibility to freeze the approved plans so that only specific users (e.g. approvers) are allowed to re-open the plan or change the same?

Reason: we use the planning approval for vacation planning and we do not want the users to simply changed already approved plans.