Hello,
I am a volunteer in the United States. The usual way to do this is to start by setting up an event page. In preparation for the event try to get people to sign in on the event page, and when you have your event get people to register there.
If during your event the group posts their work on the event page, then people elsewhere can comment on it. I can commit to comment, and I will also show the page to people in the United States and ask them for comments.
If you want to talk generally about hosting events then feel free to contact me. Thanks for your interest in this and let me know if you need more help. I can share information with you about how this has worked elsewhere.