Thanks @cibersheep for your answers, I succeed to do what I want with Content Hub and a C++ plugin to manage file deletion and renaming.
I wrote a a sample app available here: importwithcontenthub, with many (too much!) comments.
This sample app allow user to import an image, the image is stored (so that it is available on next app launch). And when user imports a new image, it is stored by overwriting the last one (only last imported image is stored).