Using While On Suboxone

So, if a person is on Suboxone and they want to use heroin or meth, how long do they wait after they have taken Suboxone to use and will it show on their drug test from the addiction clinic? We have been told that our child is using both at different times while on Sub.
My 30 year old son, heroin addict, is on suboxine for last 4 years and continues to use xanax and other pain pills. I have been told by the counselors, doctors and also read on-line that it is dangerous and he could wind up loosing his life as these combinations stops the respiratory system. Doesn't stop him though. I would think the same would apply with suboxine and heroin and/or meth.
I am sorry you are going through this. I know of no clean and sober NA person who has stays on suboxine. I cringe every time I hear the words suboxine. No one should be on it for more than a few days to detox. If they've been on a long time and want recovery, they need to wean themselves off it over a short period of time.
NOTE: the suboxine doctors of course, disagree with this. These doctors do not want to talk to people like me because I know a real lot and I also know many recovering heroin addicts and absolutely none of these people take suboxin. If they did, it was during a detex and only for a few days.
Suboxine provides a daily high and the addict will never admit this. Takes aways feelings, leaving them with just surface feelings. No highs or lows, no growth or recovery. It leaves them wanting to dip back into the drugs that supply the real high highs...they think they can get away with it without any damage. Based on my experience with my son...they just don't think with a full deck.
It's a long road we have ahead of us. They won't get better unless they want to 100%. I am finally beginning to believe my son doesn't want it fully yet. I started reading the NA Big Book and the NA 12/12. It's very informative as to the mind of the active addict.