N.C. Gen. Stat. § 15A-907: Continuing duty to disclose.

If a party, who is required to give or who voluntarily gives discovery pursuant to this Article, discovers prior to or during trial additional evidence or witnesses, or decides to use additional evidence or witnesses, and the evidence or witness is or may be subject to discovery or inspection under this Article, the party must promptly notify the attorney for the other party of the existence of the additional evidence or witnesses. (1973, c. 1286, s. 1; 1975, c. 166, s. 16; 2004-154, s. 7.)