Planetary systems form from the dust, gas and ice in discs around young stars. High-resolution images from modern telescopes now reveal complex rings, gaps and other substructures that may be linked to planet formation. At the same time, these observations raise fundamental questions: some discs show rings at ages that seem too early for planets to form, many appear too low in mass to build analogues of our Solar System, and exoplanet surveys reveal a striking diversity of planetary systems. Together, these findings show that our current picture of how Solar Systems are born is still incomplete. This COST Action builds a multidisciplinary network across three cornerstones: experiments, models and observations. Laboratory measurements provide the data needed to describe the relevant physics, inform models of disc evolution and planet formation, and interpret dust and gas emission. Modelling offers a virtual laboratory to explore physical processes and generate observable diagnostics, while astronomical observations deliver the benchmarks required to test and refine these scenarios. By coordinating efforts across Europe, the Action aims to develop a coherent framework for Solar System formation, train the next generation of researchers and communicate its findings to the wider scientific community and other stakeholders.