yes, you can sub, but get QuickFix 4.0, don't use your clean pee from a while ago. Human urine breaksdown in like 48 hours I think (without freezing temps) so chances are the piss you have is no good anymore, unless it was put in your freezer pretty quickly after you took the sample.

Don't fuck around like this though. You are on probation and they have the right to observe you at any time. Don't count on your fake piss getting you through in case on day you have to test someplace different, or the dude follows you into the bathroom... it's just not worth getting fucked by the law for a 1 hour buzz. Trust me.

I'm actually amazed they don't observe you, are you a juvenille or are your charges not that serious?