I do not have all the facts and do not understand the basis of their objections. However, generally, they are required to provide you with the responsive, non-objectionable documents in their possession custody or control. If they have the documents, and the documents are within the broad scope of discovery and are not otherwise privileged, they need to produce them. It does not matter if the doctors work for another group or what not. If they refuse to produce documents (and assuming their objections are not valid) you need to bring a motion to compel. However, it is possible that you have propounded discovery on the wrong entity. Either the right entity needs to be added as a party, or if they have no liability, then they can be served with a third party subpoena. I think you mentioned you are in arbitration. In that case, you or your lawyer should contact the arbitrator about the issuance of subpoenas.
This answer is for general informational purposes only and should not be relied upon until your entire matter is thoroughly reviewed by an attorney aware of all pertinent facts. This answer does not create an attorney client relationship.
Without having read your discovery responses and the responses, it is impossible to tell you how the court might rule.
Moreover, I strongly suggest that if you are having discovery disputes which might necessitate the filing of one or more motions to compel further responses and request for sanctions, it is imperative that you hire an attorney to do so. The court can only award monetary sanctions to cover attorney's fees but if you are representing yourself, all you would be entitled to recover on a discovery motion is the $40 filing fee.
The information presented here is general in nature and is not intended, nor should be construed, as legal advice. This posting does not create any attorney-client relationship with the author (who is only admitted to practice law in the State of California). For specific advice about your particular situation, consult your own attorney.
There really is no answer to your questions directly without knowing the specifics of your claim, the specific demands that have been made and responses received. As this is presently in some type of litgated forum., you should bring it to the attention of whoever is presiding over this matter for a determination
Disclaimer: Mr. Milligram is an attorney licensed to practice law in the States of New York and New Jersey. This response is not legal advice and does not create an attorney/client relationship; rather this response is intended to be legal education only and is intended to provide general information about the matter in question. Please note that this answer does not constitute legal advice. It is merely intended to provide educational material and general information to aid the poster in finding answers to the problem posed. This answer does not create an attorney-client relationship. In most cases, it is best to contact an attorney directly to find answers to your problems.