Secondly, if you are looking to keep the war "contained" then it cannot involve the Consortium and the Transgalactic Empire... at least, not openly. These two power blocs are the Phase World versions of NATO and the Soviet Union, circa 1985. It is commonly accepted that if they square off again in a full scale war, that the Three Galaxies will be destroyed several times over.
HOWEVER>>> that doens't mean that they cannot use third parties to hurt each other. It's called a proxy war, just like Vietnam. So it's entirely feasable to make up your own little stellar collective, breaking into civil war perhaps... with each side backed by one of the super powers?
Good places to put such a conflict include the Anvil Galaxy (which conviently has its own book) and the Tail of the Corkscrew Galaxy (which doesn't yet have a book but is a lot like Central America I can tell you). There's also a big event happening in the Thundercloud Galaxy, called the Scramble... but that book won't be available for a while
I have a fairly detailed timeline of the Three Galaxies available if you would like a copy of it.