As closely as possible, this site endeavors to remain firmly within the bounds of the "Canon" of _2300 AD_, as set out by GDW in the various Games, Magazine Articles, Modules, and Sourcebooks. In my humble opinion (IMHO), new additions are not a breach of canon... If nothing is ever mentioned about DM+11 2576 II, then anyone is free to develop it, within the bounds of canon.
What does that mean? Well, for instance; GDW says that the first interstellar probe was developed in 2136. If I write a history of the DM+11 2576 system in which I claim that an outpost was established there in 2120, then I have breached canon (the known facts of 2300's future-history), and this material then becomes not only "non-canonical", but also "anti-canonical". This type of thing is generally what I mean by "non-canonical", and is considered unacceptable for this site. Material for "alternate campaigns" will not be found, here.
In an effort to aid the interested in remaining as firmly canonical as possible, I am compiling a list of all the known historical references from all of the various 2300 products into one Master Timeline. Unfortunately, in many cases, this is showing that there are quite a few contradictions in canon, as well!
In any case, you will find numerous additions to canon, on this site, but hopefully nothing that contradicts it. I think there are plenty of new areas to develop, without having to contradict the future-history that's known.