Joining a third meeting while hosting two

Hi,

I need to HOST two meetings at the same time. I set my personal settings (In Meeting Basic) to allow participants to join 15 minutes before the meeting start time. I have also removed the Waiting Room. Question 1: Do these settings allow participants to start and join the meeting without me being there? (This is what I want)

I need to JOIN a third meeting at the same time as the two meetings I am hosting. Another user is hosting this meeting. Question 2: Can I join this third meeting as a participant while MY meetings are taking place?

I have an Education/Business account.