Hi, I would like to know how you can make this plugin show multiple killers on kill, there was something along this line in the plugin description but I never really got it to work.. so i'm trying my luck there, maybe I didn't understand and it is not even a feature but hey who knows. 

Thanks in advance

I assume by showing multiple killers you mean anyone who has contributed to the kill by causing damage.
That is not currently a feature of Death Notes, and I don't think it is advertised on the plugin page either.