Hello and welcome to JustAnswer. Please note: This is general information for educational purposes only and is not legal advice. No specific course of action is proposed herein, and no attorney-client relationship or privilege is formed by speaking to an expert on this site. By continuing, you confirm that you understand and agree to these terms.
I am sorry to hear about this situation. On this website, I do not always get to give good news, and this is one of these times.
If the Plaintiff wishes to have your supervisor as a witness, he can try to do so. He has the right to subpoena your supervisor if the Plaintiff feels that the supervisor has knowledge pertaining to the suit that would be of interest at trial or deposition.
Now, you can file a Motion to Strike Witness. For an example (from Florida) see HERE. If so, you would have to show that your supervisor knows nothing about the matter and has no relevant information to give. The problem is that this would likely involve the supervisor themselves going to court to testify that they have nothing to prove. In other words, they are likely to become involved either way - in going as a witness, or, in an attempt to have their name dropped.
As for the discovery requests, if no such documents exist, then in the reply one can simply state so. Example:
1. Please provide XYZ.
Answer: After a diligent search, XYZ has not been found. Defendant will supplement if more information is available, later.
Please note: If I tell you simply what you wish to hear, this would be unfair to you. I need to be honest with you and sometimes this means providing information that is not optimal. Negative ratings are reserved for experts who are rude or for erroneous information. Please rate me on the quality of my information; do not punish me for my honesty.
I hope this helps and clarifies. Please use the SEND or REPLY button to keep chatting, or please RATE when finished. You may always ask follow ups at no charge after rating. Kindly rate my answer as one of TOP THREE FACES/STARS and then SUBMIT, as this is how experts get credit for our time. Rating my answer the bottom two faces/stars (or failing to submit the rating) does not give me credit and reflects poorly on me, even if my answer is correct. I work very hard to formulate an informative and honest answer for you; please reciprocate my good faith with a positive rating.