Legal Advise- Criminal Law

I have joined a job at a West Australia Hospital last week. My Crim History check has not come back. Working with children check has been received. Hospital wants me to sign a statutory declaration saying I have never been charged or convicted with serious offence. I was charged with common assault 3 years ago due to complaint by my wife. She later withdrew her complaint & the charges were dismissed sine die. I have never been convicted of any offence in Australia or Abroad. Can I sign the declaration while the Criminal History Check is awaited to be able to return to work as a Junior Medical officer. The incident is already known to the Medical Board and they have not raised any objections.