How to present Facilitators to break out rooms when there is a large attendance

Hello,

We have sessions with an audience that ranges from 20-80. We do not have pre-registration for these sessions.  We want to be able to pre-assign facilitators to break out rooms. However, it would be too time-consuming to assign all attendees manually.  Is it possible to pre-assign facilitators to break out rooms but then use auto-assign for the rest of the attendees?

Thank you for your time and expertise.