Hello,
When you import the model into blender, no problem repainting it, but once the skins have been imported on the plane, they are no longer connected, she looks torn and out of place (the back of the tail).
If someone has an idea,
Thanks
Carenado support’s answer…
I have no problem to make livery, the problem is the bug with the application of texture file on the model…
You could try to contact the person that did this livery: https://flightsim.to/file/6579/piper-pa44-seminole-atp-flight-school-n833at
Different plane but is a Carenado.
Thank you but I do not have any problem to make livery for the PA44.
The problem is the Seneca, and I noticed no one has made a real livery for the seneca, the only livery I found is a customisation of the colors of the lines, and this has nothing to do with painting the plane 
But thanks 