A1:  Yes, you can present the written decision from one hearing into another to show that Boat A broke a rule and was not exonerated.

A PC may combine hearings of separate incidents that are closely related to more efficiently work out whether or not this is in fact 1 or 2 distinct incidents and to get a more complete picture of what happened. However a PC is not required to do so if the incidents are separate.

However, IMO, if during the 2nd hearing the PC starts to think that this may be 1 incident with multiple rule breaches, and the 2nd hearing involves parties that were not part of the first hearing, I might consider stopping the hearing ... reopening the previous hearing ... and start fresh with a new hearing combing both protests. 

If it was actually one incident, then it's important that all parties be present to hear the evidence and have an opp to ask Q's in the presence of all the parties. 

A2: This goes to whether or not the first breach by Boat A compelled Boat B to break a rule vs Boat C.  If the 2nd rule breach is  the inevitable consequence of the first, IMO the best process is as I described above as we are describing a single incident with multiple breaches. This is especially true as it appears that maybe Boat C was not a party to the first hearing.  

Stop the 2nd hearing, reopen the 1st, combine the hearings and start from square 1 is what I would do.

I'm very interested in hearing what others think or would do.  

Thanks, Angelo, that makes sense to me.