Hi, multipolygons like this...
https://www.openstreetmap.org/relation/19053061#map=19/-27.483575/153.012282  ...cannot share sides
https://tools.geofabrik.de/osmi/?view=areas&lon=153.01239&lat=-27.48351&zoom=19
You can either draw 
3 simple polygons 
or one simple polygon around the perimeter 
or combine these using building:part method 
or create 3 multipolygons(one for each section) and share the common ways in each.
