Okay, I only read the original topic, not everyone else, so if I say something someone already mentioned, apologies, but I'm gonna say it anyway.
First, pirates meddling? Nonsense, we don't meddle. We just decide who needs shot first.
Anyway, on to the actual post. I'd think this would be allowed, but the SCRA would have to be careful about it. They would not be able to side with RM at all.. So of RedH and RM are fighting LN, SCRA will have to fight without being in the group with RM, and will have to fire on RM after the LN are defeated, if the SCRA could win. SCRA would want both houses to be weakened, am I wrong? So RP would dictate they would try to do as much damage to both houses as possible. In some circumstances, SCRA would possibly need to stay out of the battle completely.
Like if they stumbled into an LN-RM fight were no Hessiens were present. They'd either shoot both, or neither.