Throw-in Mechanics Crew of Two (Co2)

[Zoochy]

I quickly looked in the Officials manual. I can't find it and I'm tired of looking for it.
The ball goes Out of Bounds, on the sideline, below the Free Throw Line on the Lead's side. The Lead administers the Throw-in by bouncing the ball to the Thrower. The Lead raises their arm to chop in the clock. Does the Trail mirror raising their arm to chop in the clock?
What if the throw-in is on the End Line? Would the Trail raise their arm to chop in the clock?
For a Co3, does the Trail raise their arm for Throw-ins by the Lead?
Does IAABO have different Mechanics than NFHS on these situations?