Allowing external facilitators access via participant link

We currently have SSO enabled for and configured with "Only authenticated users can join meetings".  We need to allow other external facilitators (outside our company) to access particular sessions with the participant link, so we can then promote them to co-host.  We've been sharing the host link, but this presents other problems like having the same name as the other host (which can be changed), and the last host who enters the meeting gets all the privilege's.  Do we "allow authentication exceptions" to do this, or is there another way?  Thank you.