Systems of Systems (SoS) represent a view where individual, independent systems named Constituent System (CS) collaborate to achieve overarching capabilities not attainable by a single CS alone. While CS can traditionally be engineered entities like boats or aircraft, they might also encompass human actors, positioning entire organizations to be viewed as an SoS. There is a large interest in modeling and simulation of phenomena present at different scales of SoS, which requires choosing appropriate model fidelity and resolution for the study. This thesis delves into the intricacies of modeling and simulation of mission scenarios within SoS, with a keen focus on engineered CS operating in physical environments. At the heart of the thesis lies the concept of model fidelity, examined through philosophical, scientific, and engineering perspectives. A maritime search and rescue scenario by airborne search assets serves as case study, using Agent Based Simulation (ABS) to explore the Measures of Effectiveness (MoE) of the mission. Through a hierarchical viewpoint it is studied how the model fidelity on Sub-System (SS) level affects its performance and how it aggregates up to performance on the CS level and at last the MoE on SoS level. Search scenarios are tested with different weather conditions and navigation approaches First of all, I want to express my gratitude to my supervisors who have supported me throughout this first leap of research studies, Petter Krus, Christopher Jouannet, Carina Marcus, and Kristian Amadori. You have all inspired me in research, by interesting and detailed technical discussions, by encouraging me to view research from different perspectives, and also by thoughts about life and balance in an academic setting. My research journey has so far been both exciting, challenging and brought about change in more areas than research. When I entered doctoral studies, the Systems of Systems research was shared by both divisions with a couple of us working at product realisation and a couple at flumes, it has been a great joy to get to know all of you and it certainly broadened my perspectives. I want to dedicate a special thank you to the design automation laboratory and to my PhD peers, former and present. Especially to you who kept company during the pandemic, by chatting, sending memes, and joining afternoon walks. Lastly but most importantly, I want to express my deepest gratitude to my family who are always there to support me through any challenges. Thank you, for traveling across the country to encourage me in these endeavors. No matter the distance, you are always close. Karlskrona, Oktober 2023