Susan,
I don't have anything like that in my contract. I know that the standard of proof required for FWC is 'balance of probabilities'. So I assume that if worst comes to worst, I would have good chances of winning the case because HR investigation would have to show that it was reasonable for them to believe that I made a gross misconduct. However, with my excellent performance (I won an award by my current boss) and safety awareness hopefully, FWC wouldn't find it reasonable.
I think I'm just over thinking this and planning for something that might never happen, but it's pretty hard not to do so knowing what happened in the past.
Would the document that I prepared bear any weight from HR perspective?
Cheers!