As explained many times already on the forum, GSX vehicles are NOT aware of each other. If they were, it would cost quite a bit in processing time (every vehicle should monitor all the others), and it would create an entirely new class of problems, like ground traffic deadlocks, which could be very common especially with 3rd party AFCAD, which most of the time lacks of proper dedicated vehicle paths, so they would end up using normal taxiway, creating even more problems with AI airplanes.
Instead, we try to reduce the chance they'll run into each other ( they usually don't ), by playing with delay times and starting positions. This usually works, but it cannot obviously work everywhere or with every airplane.
What YOU can do, is to adjust the vehicle starting positions, because this will have an effect on their path, the time they take to approach/go away, which will in turn have an effect on the chance they'll clash into each other.
Note that, the PMDG J41 is not internally supported by GSX, so you must create a configuration file for it and, since some services use the wingtip position to go around the wing, you should set it correctly, because it's not affecting "just" the deicers, as the name in the airplane configuration editor might suggest.
And, I suggest to download the Couatl 3 Public Beta from the "GSX Backdoor" area of the forum, because there have been a lot of improvement on this matter (amongst many other of them), and more parts of the program use the information about the wingtip position from the deicers, compared to the normal version.
