Currently an invitee can only send a request to the chair of the meeting to add other invitees. It would be useful to have an automated process to request to the chair to invite others.
This functionality was documented in a technote, but they appear to not plan on persuing the functionality.
I get complaints from users that Outlook can do this, but Notes can't. I understand the argument about it being a bad practice to invite others to a meeting that you are not the chair of, but the users want it nonetheless.