First of all, each house produces each commodity. Have buy points for everything in each house.
Second of all, each house uses each commodity. Have sell points for everything in each house.
Set up routes for everything within a single house and system, so folks can do lower profit runs within a single system/house, and have running from house to house get more profit for certain items.
Do the same with Ore, it doesnt make sense that out of all of humanity only the Kusari can refine silver, for example.
Remove the big profit routes and the general chokepoints, folks spread out.
That forces pirates to spread out.
That spreads everyone out, which over time reduces the over crowding in liberty.