Declarations shall contain the information required in § 183.191 (relating to declaration). Drivers may be changed without permission until scratch time as designated by the presiding judge. No driver shall be changed thereafter except by permission of the judges and only then for good cause. When a nominator starts two or more horses, the Judge shall approve or disapprove the second, third, and if needed, other drivers.
58 Pa. Code § 183.202
This section cited in 58 Pa. Code § 183.60 (relating to presiding judge).