question

You can already do this. You just need to add the Walls object as a member of the A* Navigator. You can do this in the A* Navigator property window by clicking the sampler and sampling the walls (not a pillar) or by clicking the Plus button and choosing the Walls object. Or you can also A connect the A* navigator to the Walls object (again not a pillar). The walls don't change color or anything, but you can tell it's added by looking in the list of members or by looking at the grid nodes around the walls.