Parent Child Work Orders and Approval Workflow

I'm trying to determine the feasibility of a few ideas we have for our work orders.  We have a special need for work orders that would seem to fit a parent/child relationship where a parent work order would define a schedule along basic info and 3 child work orders would define the resources and inventory needed on 3 separate assets.  For regulatory purposes, we have to report costs on 3 separate assets.

I have a couple of basic questions:

How does the approval workflow process work with parent/child relationships?  Would the approval be based off of the parent work order and if so, how would the costs of the child work orders be rolled up for users to approve?