Okay, now CountChildren is only returning "1", so I can only get at the first model in the heirarchy. Maybe this is an oddity of how LWConvert does it's thing? The B3D is available at the link below, if anyone can enlighten me.
http://www.optibrain.co.uk/downloads/bot1_legs.B3D
http://www.optibrain.co.uk/downloads/bot1_legs.B3D