Always stay close to the police, as you need to witness events to report back to the court. Always be respectful in your dealings with the police. This can be challenging at times as superior intelligence is not a common attribute. Their prime objective is always to negotiate. You may have to respectfully tell the constables to go back in and bring out the children, or else you will ring the senior sergeant and they will be sent back to do the job again.
Most police lack the skills required to deal with an intelligent, vindictive custodial mother.
It is easy for a custodial parent to evade the police by simply not being at a known whereabouts when the Warrant is valid. You must then attempt to track the children down and when located you can then contact the police again to execute the Warrant. If the children aren't located the police report a 'nil-find'. Because Warrants may be exercised out of a number of stations the police soon tire of wasting their time looking for children without success. If you expect trouble then advise the Senior Sergeant and they may dispatch more experienced constables.