Wow ! thank you so much for the hint, you will not belive me but I came up with a solution similar to the one you explain me, but yours is much more cleaner then mine that using 4 different textures inside a material controlled by Dynamic Parameter:
And in my emitter my dynamic parameter could get a value between 0 and 3 for every particle spawned.
I am impressed because it’s first time I ever put hand on this kind of emitters but I’m really glad for your help !