This document discusses a hierarchy process mining approach to discover process models from complex multi-source event logs collected from distributed departments. The proposed method involves three steps: 1) developing a high-level process model, 2) discovering separate low-level process models from the multi-source logs, and 3) integrating the models using Petri net refinement to replace abstract transitions in the high-level model with the corresponding low-level models. The method is demonstrated on event logs from a yarn manufacturing process to discover parallel relations such as XOR, AND, and OR.