BLT:

I'm not Official 1 nor 2, but the NFHS rule book defines a slam as:

"RULE 7, SEC. 1, ART. 1: A slam is lifting and returning an opponent to the mat with unnecessary force. This infraction may be committed by a contestant in either the top or bottom position on the mat, as well as during a takedown. A slam shall be called without hesitation."

As far as anything in the book that makes reference to "the knee" - it's not there. AS I CALL IT, a wrestler that lifts his opponent off the mat is responsible to bring them back to the mat safely. "Define safely...", hate to say it, but it's hard for me to describe and it really is how you judge the situation, move, force, "reasoning for lifting them off".

How would both wrestlers leave and land at the same time? Please elaborate.

2) Either it's a slam and called illegal, match is stopped and penalized accordingly/recovery time is started, or it's not a slam and wrestling continues. If the move results in an injury, the match should be stopped for injury time.

Hope this helps. I know a lot of people think we officials hide behind "judgement", but it is really hard to put in words as each and every match/situation presents itself with different things and you just have to be there and have a "feel" for ow the match is going to rule on your judgement. Unless you've been behind the whistle and calling a match, you just can imagine what it's like...