CA Civ Proc Code Section 2031.050

(a)

In addition to the demands for inspection, copying, testing, or sampling permitted by this chapter, a party may propound a supplemental demand to inspect, copy, test, or sample any later acquired or discovered documents, tangible things, land or other property, or electronically stored information in the possession, custody, or control of the party on whom the demand is made.

(b)

A party may propound a supplemental demand for inspection, copying, testing, or sampling twice before the initial setting of a trial date, and, subject to the time limits on discovery proceedings and motions provided in Chapter 8 (commencing with Section 2024.010), once after the initial setting of a trial date.

(c)

Notwithstanding subdivisions (a) and (b), on motion, for good cause shown, the court may grant leave to a party to propound an additional number of supplemental demands for inspection, copying, testing, or sampling.