Multiple iFrame in one page

Hey there, In our project, we have one scenario requires embedding two signing ceremony in two different iFrame div at the same time, one for each signer of a package. I am also using event notifier from this documentation: https://docs.esignlive.com/content/c_integrator_s_guide/event_notifier/event_notifier.htm?Highlight=notifier Everything works fine but my question here is, because the message returned to me is very vague like this "ESL:MESSAGE:ACTIVATE_EVENTS" , how I can identify which signer triggered the event? Thanks,