Kelly, there really isn't a need to involve the concept of multiple Clients in this.
In fact, technically the CP is very simply an Org.Management object - just like all others. As such, it is defined by a short and long text, has a start and end date, and can be assigned any number of standard or custom relationships.
Once activated the Global Employment functionality, at hiring time each employee is assigned automatically a PERNR and a CP - the object P and the object CP are tied by a relationship... at re-hiring time, the system searches for omonyms based on VORNA, NACHN, and date of birth (standard PII items), and proposes the creating
All this goes to say that it is simply DATA, and it is resident in the live, production client used by each customer.