I'm Doug, and I'm very sorry to hear of your situation. My goal is to provide you with excellent service today. I am a CA licensed attorney and have more than 30 year's experience handling employment law issues.
Have the attorneys, or has the Plaintiff, made a settlement demand on you yet? Is so, what are they asking for in terms of a settlement?
I certainly empathize with your situation, as it is never pleasant being on the receiving end of a lawsuit. However, you are wanting to accomplish a couple of things that are impossible to do under present CA law.
You have no way to force the Plaintiff to abandon her lawsuit and submit her claim to the labor Board. Neither do you have the legal right to represent your S Corporation in court. A lawsuit filed by you against the attorneys representing the Plaintiff would be entirely without legal merit and you would almost certainly find yourself being sued once again for malicious prosecution by the law firm as soon as they succeeded in having your suit thrown out.
None of your facts suggest that the attorneys are seeking a class action status, and as far as you not paying her for her breaks---even if she did sign out for her 15 minute breaks, she was entitled to be paid for them. Only a meal break need not be compensated for.