Multi-Board Integration
The schematic editor is the KiCad schematic editor with the Agent sidebar. When opened from a sub-project of a multi-board container, it gains multi-board awareness that standalone projects don't have. For everything else (placing symbols, wiring, labels, hierarchical sheets, ERC, libraries) the stock KiCad documentation applies.
Connector pins define the boundary
Connector symbols on a sub-project schematic define the multi-board boundary. Every pin on a Connector symbol is a candidate to appear on the multi-board schematic as a module-block pin.
Changes to connector pins are not pulled into the MBS automatically. After editing them, refresh the MBS.
Cross-board net names propagate
After syncing the MBS to PCB, connector pads on the PCB carry the cross-board net name. The schematic feeds PCB net names, so the schematic's label on a connector pin is renamed to match on the next ERC/sync round-trip.
ERC and cross-board checks
A sub-project's ERC runs mostly against its own schematic. One cross-board check (Connector pin unconnected) fires here too: it flags connector pins that participate in a cross-board net per the container's topology but are dangling locally.
The other cross-board ERC checks (unwired module pins, single-endpoint cross-board nets, pin-type mismatches at boundaries, label shadowing, etc.) run only when you open the MBS and run Inspect → Electrical Rules Checker there. Both passes are needed for full coverage. See Cross-board ERC checks for the full list.
Net classes inherit from the container
A sub-project's schematic inherits the container's net classes, shown alongside any local classes in Schematic Setup → Net Classes with a SHARED / LOCAL / CONFLICT status. When a local class matches a container class by content, it's promoted to SHARED automatically. When the same name exists on both with different field values, the Net Class Conflict dialog asks whether to use the container value, keep the sub-project value, or skip the class. See Net Classes for the full replication mechanism.
