Method or add-on for doing approvals for entire chain of command?

[Jason Freeman]

We are willing to pay for an add-on for this if necessary.

We have a workflow where the requestor has to use a User Picker field to choose every employee between him/her and the president of the company for approval.  In other words, every, the requestor's entire chain has to approve the request.

The issue is that, sometimes, users are not selecting the correct approvers.  They may leave out approvers, either intentionally or otherwise.

Ideally, the requestor would submit a ticket, and the workflow would find their correct chain of command.  The requestor wouldn't need to select any approvers at all.

Just for reference, some requestors have one approver, two approvers, three approvers, four approvers, etc. So we would need a very flexible way to do this.