Out-of-office functionality - add an OOF on a single workflow, activity, during a period of time

Being able to add an out of office for a single workflow, during a period of time, on a specific activity.

Business Case:

Users wanted to be able during their holiday to give access to an assistant to be able to resubmit requests that have been submitted in case it came back to the requestor but not to be able to validate the latest step that is done by the same person on an approval process.