RelatedPerson employer

How would I include an employer in the RelatedPerson resource?
I see the Patient does this by means of Contact.Relationship.Coding.Code = “E”
RelatedPerson doesn’t have a Contact construct that I can see.

The use case would be:
Patient is John Brown, age 5.
His Account.Guarantor is his father David Brown (RelatedPerson)
I need to know David Brown’s employer, since he is responsible for payment.