@julien-moreau , how to do this ?

Damned !

You'll find the CMeshSceneNodeInstances files in CP3DEngine/Engine/Scene/CMeshSceneNodeInstances.

The goal is to create a pointer to a mesh scene node that supports instances
Typically : cp3dEngine->addMeshSceneNodeInstances(...) for example

And then say :

• myMeshSceneNodeInstances->addInstance(SInstanceParams params);
  where "params" should be a strucuture with the instance's position, rotation, scale for the moment

To get an instance we we should call :
myMeshSceneNodeInstances->getInstance(indice);

IMPORTANT :
A CMeshSceneNodeInstances must be a IMeshSceneNode (then, a ISceneNode), but specialized. So you'll have to add a IMeshSceneNodeInstances.h file that will heritates irr::scene::IMeshSceneNode

When I try to move a son object, it runs away !!