My guess is GBC's done the deed at their place then called his father who'ds driven up to Kenmore, parked in the Village car park (directly behind the bus shelter) and has gone to wait at the bus stop so GBC can pull in and pick him up on his way through to Mt Crosby to dispose of the body.
GBC may have pulled into the village on the way back to get rid of evidence in industrial bins which are on the bus-stop side of the village (afaik). All this coming and going from the village would have been right in the sights of the traffic camera. This explains the industrial bin lead and how they knew to look there.
i think you are probably pretty close here - only problem is i noticed yesterday that there are signs at the car park entrance saying that the car park is closed off every evening
i am also thinking that NBC is def involved though - the family dynamics make it pretty clear that he would be the go to man if things went pear shaped
IMO