It is great when any business owner gets a referral from a past client or customer. In a normal retail setting, it is natural to get updates on the person's satisfaction with the services or product.
However, in the legal and medical field, just stay out of the relationship. Once you refer someone, you have no right to receive updates from the professional. Of course, you can always ask the customer about the medical service and status, but stay away from the attorney-client case if it is in litigation.
Attorney-Client Privilege and Work Product
The law protects communications between attorneys and clients so the clients can freely discuss cases, and the lawyers can freely give advice, collect information, and formulate strategies. However, the privilege can be waived by the client when he insists on (1) bringing in third parties on phone calls and meetings; (2) disclosing conversations or strategies on social media; or (3) discussing advice with friends and family. During discovery, opposing counsel can find out the identity of those individuals who had to stick their noses in litigation. This could be disastrous because once the privileged is waived, opposing counsel can learn strategies and topics of communication.
Settlements
The nosy friend or family member could be a disaster to your settlement. Settlements are often confidential. This means the parties are prohibited from discussing the terms of the settlement. A persistent and intrusive person may push you in disclosing the terms. If your opponent learns of the settlement violation, you may be ordered to return the settlement and pay attorney's fees. If the person wants to know what happened, tell him it's been resolved and shut down the topic.