In our internal network of 172.20.0.0/16, I have Dude (v3.0) set up to discover certain Class C subnets and NOT to discover the Class B level. So I can delete the Segment #0 172.20.0.0/16 network item from my map, and let loose the discovery processes (like 172.20.1.0/24, 172.20.2.0/24, etc.) but 172.20.0.0/16 ALWAYS pops back up on the map with automatic link lines drawn…VERY annoying. 
Is there anyway around this?
I’m a former programmer and database administrator who is now being a network admin on a small private school network and so this is a bit over my head, but I’d really like to get Dude to work well for us as it would be quite helpful. This problem, however, sort of stands in the way of effective graphical use of the tool. (my ignorance stands in the way too!) 
Thanks!