How to reassign document for approval to another user?

Following.  Also curious if this is possible, but under 2 scenarios.

1. Self-Managed delegating approval while I am on vacation.
2. Approver in one step directs the “next approval” step based on which supervisor is scheduled to work this shift.  I know this one can be done to some extent by putting them all in a workgroup, but I want the on-duty approver to get the notification where the workgroup has a static primary owner.

@brianstevens Unfortunately no one has suggested ways to accomplish this.  I’ve also come up empty asking my colleagues.  I’m assuming it can only be handled procedurally somehow.