Add user to Meeting using Update-MgUserEvent - powershell

Question

I'm trying to add a user to an existing meeting using "Update-MgUserEvent."
I can pull the existing event fine. However, I'm having trouble merging the existing attendees and the new attendee into something that the command will accept. Anytime I am close, it will add the new attendee and send cancellation requests to the existing attendees.
If anybody has any tips or any help at all, it would be GREATLY appreciated! Here is what I am working with so far. I'm trying to merge the "$New Attendees" and "$ExistingAttendees" data and send it back to the event as an update:
# New user to test.
$NewAttendees = #{
Attendees = #(
#{
EmailAddress = #{
Address = "bill.cosby#test.com"
Name = "Bill Cosby"
}
Type = "required"
}
)
}
# Get user start date.
$EmpStartDate = Read-Host -prompt "Enter employee start date (YYYY-MM-DD)"
# Get existing events.
Clear-Variable Existing*
$ExistingEvent = Get-MgUserEvent -UserId "michael.scott#test.com" -filter "Subject eq 'I.T. Orientation'" | Select-Object Id,Attendees -ExpandProperty start | Where-Object {$_.DateTime -like "*$EmpStartDate*"}
$ExistingAttendees = #{
Attendees = #(
#{
EmailAddress = #{
Address = $ExistingEvent.Attendees.EmailAddress | Select-Object -ExpandProperty Address
Name = $ExistingEvent.Attendees.EmailAddress.Name
}
Type = "required"
}
)
}
# Update the event.
If ($ExistingEvent) {
Update-MgUserEvent -UserId "michael.scott#test.com" -EventId $ExistingEvent.Id -Attendees ?????
}