No, this would be a fraudulent enlistment prosecuted under Article 94, UCMJ, if discovered.
ADD and associated treatment can a disqualifying condition unless it "resolved" before age 12, and /or you have not been on medication for 12 months prior to enlistment.
He can submit a request for extended leave, or potentially a humanitarian re-deployment. However, this is rarely granted in his situation. The circumstances for you at home would have to be very extraordinary and well documented for him to have a chance. Absent the extraordinary nature of the medical concerns they would view his request along the lines of "lots of people have family problems, why is yours different."
You have to put in a request. It is up to the discretion of the command whether or not they will let you revoke your waiver. Get with military defense counsel ASAP. Somewhere in your notication letter it says that.
They can testify.
There may be issues about credibility, especially if there is evidence of "planting drugs."
Get a good criminal defense lawyer from that area. It's quite possible H/she knows the officer and his history if they do a lot of drug cases in town.
Go back and read the contract you signed.
It is likely you signed a contract for six years active, and two years inactive Reserves. There are some contracts for less, and for more, depending partly on what branch of the Army you are to serve in.
It looks like you have reasked your question with some more facts.
There are some more comments on your first question, look those over.
If he is still on active duty there are some things you might be able to do to help better the situation.
1. This is not something you should be discussing on an open forum like this, where people can read this.
2. If you have since been discharged, then you should be OK. The situation you read about is certainly egregious, but your case doesn't seem like that. Also, there's nothing based on what you've said that clearly establishes you should have been DQ'd.