In this paper, we present an extension to existing approaches that capture and exploit timing-correlation between tasks for scheduling analysis in distributed systems. Previous approaches consider a unique timing-reference for each set of time-correlated tasks and thus, do not capture the complete timing-correlation between task activations. Our approach is to consider multiple timing-references which allows us to capture more information about the timingcorrelation between tasks. We also present an algorithm that exploits the captured information to calculate tighter bounds for the worst-case response time analysis under a static priority preemptive scheduler.