If Live Tracker data was feed into the RadarBox user network this would not affect RB Sales if anything would increase selling power.
Feeding RB Data into the Live Tracker network does hold a problem as it could render the RadarBox not required!
Suggestion 1 Then:
With other options available for obtaining networked data from RB (via Plane Plotter) and the possibility of this growing to obtain network data via PP from both currently available boxes then the need to justify a network fee is growing.
How about revisiting the network fee overall in conjunction with two feeds of data into one: One from RB Networked boxes, the other from Live Tracker Network all available for one network fee!
This would enhance the Radarbox network and features thus should give more to the potential buyer. It does not help any current Live Tracker user, but I can see how it can without the possibilities of affecting sales of RB.
Even though I'm typing this, and think its a good workable idea, it still leaves the issue of will users "pay" for a network fee when other free options are available. On this I've no idea, even I cant answer that one for myself! I guess it depends on the amount, I'm working on current fee.
Suggestion 2
Build the other software into RB in the same way as you have with Acars. So you'd need to own each package before you can link them together (somehow!)