More planets, more connections. I think this does cover all Piper stories.
And again as a PDF: piper-systems
A lot of the planets are just mentioned by name, never in actual relation with any of the other worlds.
One thing I did not include in the chart yet is that Marduk is probably relatively close to Baldur, at least the two exchange diplomats. Still, since ships regularly make 3000+ light year jumps, that does not necessarily mean actual proximity.