Thanks for your very fast answer Juanjo !
Well it's because i am a total has been and was still using the old Shop context to work with octane.
As LiveDB still import shaders in Shop i have the wrong feeling that it was still the default context for octane.
But indeed i have just double check , in the new mat context things work perfectly -> subnetwork if you need but not an obligation !
So now can we consider shop kinda legacy with octane like for mantra ?
In that case that would be great to also have the ability to import liveDB in Mat context, and create the render target node in Mat context
in order to get one consistant context to store octane nodes.
Thanks again for your help !