snap over punters head----safety?

[rsevign1]

No live ball foul by B, safety on A whether they commit a live ball foul or not.
Live ball foul by B and no foul by A; enforce penalty for live ball foul by B (no safety).
Live ball foul by A and live foul by B should result in off-setting fouls and a replay of down.

So the best thing to teach the kicker, assuming he can't legally kick ball into field of play is to backward pass such that it goes out of bounds in the end zone. No live ball foul if the kicker muffs his attempt to gain possession and the ball goes out of bounds in the end zone, but this relies on judgment by the covering official.