Abstract-Process-and data-centric software systems require a tight integration of processes, functions, data, and users. Thereby, the behavioral perspective is described by process models, while the information perspective is captured in a data model. Eliciting and capturing requirements of such software systems in a consistent way is a challenging task, demanding that both process and data model are well aligned and consistent with each other. While traditional software modeling languages do not allow for an explicit integration of data and process models, activity-centric process modeling languages tend to neglect the role of data as a driver of process execution; i.e., business objects are usually outside the control of the process, normally stored in external databases. To overcome this drawback, PHILharmonicFlows provides a comprehensive framework for enabling objectaware process support. In addition, a sound specification of process-and object-centric software systems becomes possible. In this paper, we present a requirements modeling approach that provides methodological guidance for modeling large processand data-centric software systems based on PHILharmonicFlows. Such guidance will foster the introduction of respective software systems in the large scale.