There were a number of questions/answers here somewhat related to this question, but not exactly the same. I am developing an inverter with half bridge MOSFETs with high voltage and current over 100 amperes using parallel MOSFETs.
MOSFETs drains are connected to the copper power bus which will mount outside of the PCB. All the components are undoubtedly part of the same schematic as some of the MOSFETs pins are placed on PCB traces, but a chunk of circuits will be outside of the PCB.
This is a common task for motor controllers and for power supplies, but I can't find guidelines on PCB design. Whatever PCB CAD software is used, the rule check will fail in unconnected parts of the schematic. Please share your experience.
Note: I am using DipTrace for schematic and PCB design, but the workflow should be similar for any CAD to fully use capabilities of CAD and yet escape DRC errors.