Hi Marc,
Many thanks for your accurate answer !
You understood it perfectly well : my plan consist in mimicking a CD changer to install a Phibu BT module behind my Wipcom3D. Two kinds of modules can be bought but the only one that keep most of all the steering wheel commands active (VOL +, VOL -, FF, FR) has to be pluged on the CD changer connector. However, this module won't be able to display any tracks listing or titles on screen (which I don't mind). Guess that I will have something like "CD changer #X" on screen instead (

).
Here is the french webpage that sells the module I'm talking about. The module is sold as RD4 compliant so it will be CAN compatible.
https://www.phibu-electronics.com/nouve ... 2x34599710
According to your explanations, I'll have to use the 12 pins type #1 connector (wich is oriented) on the separate C block of the picture above.
Last step : activate the CD changer option using a Diagbox
I think that I'm correct here.
Btw, what are the other connectoers on the WIPCOM3D for ?
Cheers ! (and happy easter !).
Franck.