Family Honeymoon (1949)

Grant Jordan, bachelor botany professor, marries Katie, a widow with three kids, despite the machinations of Grant's former girlfriend Minna. But on the wedding day, Aunt Jo, who was to babysit, breaks a leg; so the kids come along on the honeymoon. After misadventures en route, they make it to the Grand Canyon, only to find Minna there, still scheming.