The Pennsylvania Supreme Court answered three related questions regarding underinsured motorist (UIM) coverage. The plaintiff was injured in a car crash. He recouped $25,000 from the striking motorists’ insurance company. And he received $25,000 more from State Farm, his insurer, under his UIM policy. He then sought $50,000 in UIM coverage from his mother’s State Farm policy because he was a resident relative. First, the Court held that the form signed by the motorist’s mother waived only intra-policy stacked UIM coverage but not the inter-policy stacked UIM coverage in a multiple-vehicle policy at issue here. Second, the Court held that the household vehicle exclusion in the mother’s policy did not bar coverage for her son. Third, the Court concluded that the coordination of benefits provision in the mother’s policy could not serve as a de facto waiver of inter-policy stacking.