Curative amendments shall be filed in accordance with the requirements of section 609.1 with the municipality within which the landowner's property is located: Provided, however, That the governing body before which the curative amendment is brought shall not have the power to adopt any amendment to the joint municipal zoning ordinance without the approval of the other municipalities participating in the joint municipal zoning ordinance. The challenge shall be directed to the validity of the joint municipal zoning ordinance as it applies to the entire area of its jurisdiction.
53 P.S. § 10810-A