N.Y. Comp. Codes R. & Regs. tit. 12 § 325-1.7
A physician authorized to treat workers' compensation cases, when requested to supersede another physician, must, before beginning treatment of such patient, make reasonable effort to communicate with the attending physician to ascertain the patient' s condition. The superseding physician must also advise the attending physician of the name of the person who has requested him or her to assume care of the case and state the reason therefor. If the superseding physician cannot contact the attending physician, and the claimant's condition requires immediate treatment, the superseding physician should advise the physician previously in attendance within 48 hours that he or she now has the patient in his or her care. The preceding physician shall supply the superseding physician with a complete history of the case.
N.Y. Comp. Codes R. & Regs. Tit. 12 § 325-1.7