Temporary signature authority enables a person who has been asked to provide a signature to assign that task to another user. A user with temporary authority can view and advance or move back all signature documents that are currently owned by the original signature authority. Tasks assigned to a user with temporary authority also appear in the Action Items list of that person.
Not exactly, giving TSA would work in certain situations. However, we need the ability to re-assign individual tasks within a workflow. We wouldn't always want the person given TSA to receive all tasks for the original owner, but rather we need the ability to pick and choose which tasks get re-assigned.