Ah well, might as well forget this one.
I've just checked and this "issue" was raised two years ago in the Bakery and nothing has been mentioned anywhere lately, so I guess Aim Assist in the Busses area is never going to happen.
I realise that we now have Aux Tracks, which I have played recently, and that they can appear anywhere, of course, so perhaps I need to grasp the nettle and use them more...
cheers, and thanks
andy