I spent my whole weekend........

Downloading PAI packs and AFCAD files.for FS 2002......now a question how do you guys assign parking spaces to airlines?
IE how do i keep AA planes from parking in UAL gates
I added some AI traffic to my home airport of KDSM i worked there for 2 years as a refueler and never once did i see a AA
IE how do i keep AA planes from parking in UAL gates
I added some AI traffic to my home airport of KDSM i worked there for 2 years as a refueler and never once did i see a AA