weighing my options

If you want to risk damaging your name with the old company, just go ahead and do what you are planning to do. The wise thing to do is to keep your intentions from the company. However, they will find out what the deal is when you tell them you are not available for a new client when your present family takes their case to another agency. They can not stop you from changing employers and you can not force them to be a good reference. No noncompete paper, green light. But don't expect glowing recommendations. They don't have to say you were a good employee and don't expect to be welcome back with them. You are the one who has to make the decision. Just be aware that people work for more than one agency all the time. However, there is a way to go about it without being accused of taking business away from an employer. Make certain that the family does not breathe a word about taking you with them. If the agency people say something to you, tell them that it was your decision to stay with a case that made you happy. Offer to work a shift or two on another case. That is the best you can do for them without totally burning your bridges. But if they bother you that much, then the better thing to do is to submit a letter of resignation. Look at the employment picture in your area. How many agencies are there? Will you possibly need these people in the future? I wouldn't worry about legal problems, there aren't any. Good luck with your decision.