Hi Didier,
Subfleets are a group of aircraft in everyone’s case, it is not something special for you. It is their design logic, they hold the fleet with same specs And making subfleets only by aircraft model is not something logical too (you can check the guides about it, how real world subfleets are divided/handled etc).
Anyway, with your logic, an aircraft (B738) represented by multiple addons, having custom airframe match at aircraft level will not work either. Imagine a scenario in which you are simulating an airline with 2 B738’s in its fleet. But you have 5 different addon developers in 4 different simulators, which your pilots own and wish to use.
What will you do then ? Add fake aircraft to your fleet to cover all possible addon matches ?
A320 : Flight Factor, JarDesign, Aerosoft, FBW
B738 : Zibo, LevelUP, iFly, PMDG (2x 'cause they are different for FsX and Prepar3D, soon for MsFs probably too)
MD8x : Rotate, Leonardo (2x)
examples can be extended to other models easily.
And the worst result is, by making an aircraft “Zibo” only will mess up things during flight operations. You have 3 pilots using X-Plane, they want to fly at the same time but you have only one X-Plane/Zibo matched aircraft. One pilot will pick the best aircraft, others will be forced to use the ones with iFly or PMDG specs. Then a poor Prepar3D pilot will find himself/herself in a mess
So in short, your theory/request (having custom airframe match at aircraft level) and what phpvms v7 currently offers (having it at subfleet level) fails Or at best works only if you are simulating one addon and using one simulator (like X-Plane and Zibo only VA or MsFs and FBW only).
This is why, I built the “Addon Specs” logic (fine tuned it in time according to user/va feedback and needs we discovered along the way), which can support almost all possible scenarios and has the flexibility of being used in multiple ways Like creating a “new” aircraft model which Simbrief does not support yet (like A21N), fine tuning default simbrief options for a specific addon or just using multiple pre-built simbrief aircraft profiles within a fleet.
Maybe you should check this forum to find the answer of your own question, there is a nicely organized " Downloads" section here, link is at the top
Good luck and safe flights
Addition: Your request and partly phpvms v7’s current design CAN work only when you allow an aircraft to be used by multiple pilots at the same time. Which is not realistic of course but can be a solution if you are aiming to have a relaxed setup.