Create a view with just the Grid (on a grid layer) and a registration hotspot on the Archicad layer
Place this view on a Col layout using the hotspot to locate the view.
Place the same view on the wall layout but this time cut a hole in the placed view to cut the unwanted lines.
This method allows a single grid layout.
Hope this helps
Archicad 4.1 to 28 Tech Preview. Apple Silicon
you can't build a line
Mac Studio
iPad Pro
iPhone