$0.02
Always pre-game this situation..however, I must admit I would disagree ( doesnt mean I wouldnt follow it!) with the Fed procedure.
First, if it is even close and I am not in perfect position, I will wait a breif moment before I signal the try as a three and take a glance at the partner who may have been able to see if he was indeed behind the line. If one of my partners does this to me, I am now taking responsibility for the call, and signalling the try or pointing two towards the floor.
If I believe it is a three and get nothing back from my partner on the glance, I'm going up with the three. If I am not sure, I'm not making any definitive signals....and we move on with the game and the bucket counts for 2 ( which all field goals do unless you signal otherwise..although I have a few partners who INSIST on signaling two on every bucket..lol)
Now here is where I differ in the procedure. In the situation I just described above, if there is a question by ANYONE as to the points on that particular shot, my partners and I will discuss it during a normal stop in play...ie ball out of bounds, foul, etc. If, as the original scenario described in the post, I signal 3 and THEN my partner ( who better be 3,000% sure ) signals a two, my partner wins without discussion EVERY SINGLE TIME.
The two fingers pointing towards the floor is a definitive gesture signaling to EVERYONE that, although it was close, the shooter was not behind the 3 point shooting line. If one of your partners " changes your call " on this one, you roll with it, because if there is any disagreement, the call is now on his shoulders. That is ok, because you TRUST YOUR PARTNER that there was a reason he made the definitive signal.. and you get your a** in better position next time.
All of this can be done inside our lil world of officiating. without blowing your whistle and stopping play, and letting everyone else ( people like that Wildcat FanATIC I was reading about in past posts ) know that it is possible that one of us was out of position, or a completely blind idiot.
If you are that certain of the 3-point and your partner does this Dan ( is that who is arguing the point? ), wait until a timeout, come together, place your hand over your mouth, keep a straight face..... and rip his a** a new one. ( wait until halftime when applicable) Then move on with the game as if it never happened.
**IMHO IMHO IMHO IMHO IMHO IMHO
Savaahn Ty