3+ armies and shooting into CC

We all know that you can't shoot into a CC battle when there are just two armies and while I don't think there is anything anywhere about more than two armies and this likely comes down to a house rule I'm curious where you all fall...

If you have 3 or more armies in a free for all and 2 armies are engaged in CC, should the third army be able to shoot into that not caring who he hits? I believe so but thought I'd see if anyone thought it shouldn't be that way and why...

I don't see why not. The rules don't deal with the situation so you would need house rules to clarify what is allowed.

There was a situation like this on the rulebook, about 3+ games. It said something like that if there is a combat that you are not part of you can shoot in it and resolve wounds just like its one big unit.