The current docking system supports these airplane types:
All Airbus from A300 to A380
All Boeing from 707 to 787
CRJ 700/200
DC9 and DC10
All MD series from MD80 through MD90
MD11
CRJ 145/190
ATR 42/72
Concorde
Dash8
Once an airplane is recognized, it doesn't matter who made it, provided it has a GSX configuration for it. However, it's not possible for users to add new airplane types.
This is how the current system works, which is back-compatible with FSX and because of this, it's limited in the number or airplane types it can support, because adding a new type would mean adding new animations and recompiling all the variants. This, in addition to be time consuming for us each time a new airplane type is added, affect performances, because the models will grow larger as new airplane types are added.
We are not going to update it, because it will go away soon, to be replaced with a more advanced DirectX-based system in P3D4, which will go away with the animation system entirely, and will be able to work automatically with any airplane, as long it's configured for GSX.