The metadata for describing a Parent-Child relationship simply requires listing the possible Parent or Child types for each entity. In the following example, a Parent-Child relationship exists between Paid Employment (Parent) & Employment Address (Child).
From PaidEmployment.xml (i.e. the XML to describe the Paid Employment entity):
<Relationships> <Child name="EmploymentAddress" /> </Relationships>
From EmploymentAddress.xml (i.e. the XML to describe the Employment Address entity):
<Relationships> <Parent name="PaidEmployment"/> </Relationships>