Rebound throw/tip to back court- violation?

[firedoc]

If A2 tapped the ball into the backcourt-no violation. If he caught the ball and then threw it into the backcourt - tweet...violation because team control was then established.

I'm not sure what you mean by him being over the plane of the endline. If his feet are inbounds he can certainly hold the ball over the endline without a violation occuring.