Safety-critical applications could benefit from the standardisation, cost reduction and cross-domain suitability of current heterogeneous computing platforms. They are of particular interest for Mixed-Criticality Product Lines (MCPL) where safety- and non-safety functions can be deployed on a single embedded device using suitable isolation artefacts and development processes. The development of MCPLs can be facilitated by providing a reference architecture, a model-based design, analysis tools and Modular Safety Cases (MSC) to support the safety claims. In this paper, we present a method based on the MSCs to ease the certification of MCPLs. This approach consists of a semi-automated composition of layered argument fragments that trace the s...