Solus,
I believe that is the anathema of civil war. There is nothing civil about it. It is brother against brother and sisters are not exempt. If your family becomes fair game then so does theirs! Perhaps this is why there is a voice in the back of my head that says it must be avoided if possible. If not avoidable, I remember the words of the Ayatollah Kogani:
"If you are going to pre-empt,
Do it first."