Creating Multiple Routes

I've finished setting up all the stars in my sector, with populations. My next step is to create routes between certain populated stars, not all of them. The idea is that only a certain core group has advanced from a collapse enough to go back to the stars. Players will be able to cash in on the discovery of systems that are populated from before the crash.

Anyway, Sol is the core and the maximum route length is 9.7849 ly (3 pc). So, I need to create routes that will connect all populated systems that can trace a path of connected routes, eventually, back to Sol.

So, I start with the following query based on Sol; Systems with, Population > 1, Within 9.7849

I then select all of them, click on Create Proximity Routes, click the Selected Systems Only radio button, fill in the Max Route Length and Max Routes per System fields, and click OK.

All fine and dandy.

Now, I need to get he next layer. I figured I could use the same query, but that would also return systems that have already been assigned routes. Including them would create duplicate routes, so I need to exclude any systems that already have routes. this stymies me.

I can't use the Populated Systems Only radio button on the Create Proximity Routes dialog, because that would build routes between systems that cannot trace a path of connected routes to Sol (I know, because I tried that).

Any ideas on how to do what I'm trying to do?

Thanx!