It sounds like you are trying to handle a cancellation proceeding without retaining legal counsel. Sorry, but it would border on malpractice for me to begin to advise you on the specific question you have asked. You cannot possibly navigate through the complicated procedural rules without legal counsel---your adversary will take advantage of your inexperience and lack of legal training to your great disadvantage. What needs to be done----get a lawyer to deal with this problem. Don't even think about trying to deal with the inadequacies of your prior submissions without legal counsel. Is this trademark important to you? Then invest the reasonable fees required to pay for legal counsel.
Note that if this trademark is owned by a company, you may be breaching fiduciary duties to the company and its stockholders if you try to get away with handling a matter like this without legal counsel. Do yourself a favor and stop trying to play lawyer.
The Rules of Practice for the TTAB and the Federal Rules of Evidence govern cancellation proceedings generally including the requirements for introducing evidence. Although these rules are available on-line, they are complicated, especially for someone without formal legal training. Your question does not give enough detail for anyone to be able to answer. Do you want to supplement your discovery responses? Do you want to know how to introduce evidence to support your case? I suspect you are not sure yourself, which is why you should seek qualified trademark legal counsel.
Comments provided on this website are not intended as legal advise and do not create and attorney client relationship.
To add to my colleagues' comments, we do quite a bit of work at the TTAB and I and my partner both would have to consider the specific circumstance and look at the rules before coming to a conclusion. I am also inclined to agree with Attorney Ross that it would not be appropriate for us to offer an answer assuming we thought we knew it because if we were wrong not knowing more and you relied on that response we failed you and ourselves.
These are complicated matters, this you know. I think you should reach out to several TM lawyers for a free phone consultation to discuss your case and get some insights and see if you can find a professional to work with so you stand a better chance of prevailing here.
DISCLAIMER: this is not intended to be specific legal advice and should not be relied upon as such. No attorney-client relationship is formed with the law firm of Natoli-Lapin, LLC on the basis of this posting.
Q:"Can I submit additional exhibits after discovery is closed at USPTO cancellation proceeding ?
A: You CAN but shouldn't. That's a job for an attorney. You are here asking an attorney because you don't know what you can and can't do procedurally. That should tell you that you need an attorney. As to whether additional exhibits should be submitted after close of discovery, that depends on many factors and the overall strategy. For example, are you contemplating submitting them to the other attorney or to the TTAB or to both? Your question shows you are in hopelessly over your head, as you are hung up on procedure and likely in even worse shape on the substance. Procedure at TTAB can make or break your case, and if you continue pro se, likely break.
Q:"What needs to be done. . .?"
A: That is easy. What is needed is for you to hire a trademark attorney familiar with
TTAB proceedings or at least legal proceedings under the FRCP and administrative proceedings. Why would you do otherwise with something important enough to be in such a proceeding in the first place?
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.