Multilevel tracking

Given:
Three Events:

  1. Users arriving from facebook
  2. Users arriving from a website X
  3. Users placing an order.

Problem Statement

Tracking number of users that arrived from facebook to website X and placed an order.
Tracking number of users that arrived from website X and placed an order.
Tracking the users who made this journey, eg- User A took journey from facebook to placing an order.

How do i track this via piwik? According to my current understanding, I am only able to track one level of hierarchy, but I am confused when it comes to multilevel hierarchy and tracking it.

P.S: This need not be a 3 level case. Thus, writing the problem statement in the most general way,

How do I track the number of users that navigated through event A to event Z via n number of events in between.
How do I track the user’s full event traversal activity?