[teams meeting] How to change guest user role ?

Hi,i created a meeting where everyone was the presenter by default,add two users to the meeting (one for the organization and one for the guest)

Now, i want to set the user of the organization as a attendee, and the guest as the presenter

Here is my code, after which everyone becomes a attendee..

                var onlineMeeting = new OnlineMeeting
                {
                    AllowedPresenters = OnlineMeetingPresenters.RoleIsPresenter,
                    Participants = new MeetingParticipants()
                    {
                        Attendees = new List<MeetingParticipantInfo>()
                    }
                };

                var attendeeList = onlineMeeting.Participants.Attendees.ToList();
                attendeeList.Add(new MeetingParticipantInfo
                {
                    Role = OnlineMeetingRole.Attendee,
                    Identity = new IdentitySet { User = new Identity { Id = "organization user id" } }
                });

                onlineMeeting.Participants.Attendees = attendeeList;

                return await _GraphClient.Users["user id"].OnlineMeetings["meeting id"]
                    .Request()
                    .UpdateAsync(onlineMeeting);