getting started with this new ‘family culture/ethos’

guidance re. how should we handle starting this TSG process, in the context of fairly serious hostility and dishonesty
– eg physical violence, stealing, vandalism, calling 911 and saying parents are attacking/hitting him (while tantruming, fortunately the police are aware of the kids' issues/ needs – and the child did acknowledge he was lying, with the therapist and with the police officer)