How to add related record to Contact (contact within a contact?)

How to add related record to Contact (contact within a contact?)

I am just playing around with CRM. We are using it for social services and I turned the contacts Module into Clients. Many of the clients have the same case managers but there is a high turnover so I would like a way to have XYZ Mental Health Agency with John Doe as the case manager. If he leaves and Mary Smith replaces him I want it to update all the clients records automatically. I am wondering if I should use Accounts to keep track of agencies and their employees who service our clients.

Thanks in advance!