Achieving net-zero targets by 2050 requires decarbonisation efforts across multiple sectors. Through electrification, hydrogen, or cross-sector value chains, sectors are coupled, and system boundaries redefined, leading to new, but to date hardly conceptualized multi-system configurations. This contribution proposes five distinct multi-system configurations: unconnected systems, emerging connections, interconnected systems, integrated systems, and new system emergence. For each configuration, the systemic dimensions including technologies, institutions, and actors are conceptualized and the strategies of system entanglers are defined. Shifts in system boundaries and the site of interaction, understood as the dynamic space in which systems interact, are characterized. The empirical illustration is based on a comparative case study on coupling the electricity sector with industry, mobility, and heating through green hydrogen in Germany. This contribution advances multi-system research by conceptualizing multi-system configurations, understood as dynamic “stages” of system interaction involving shifting system boundaries, changes at the site of interaction, couplings, and system entanglers.