Meeting invite - Hidden Attendees

Hi,

Hope someone can help.  

I have sent a meeting invite but used the web access of outlook and hidden the attendees so they can't see who has been invited - the only problem is I can't see who has accepted the meeting invite.  Is there away around this?  When I go to tracking it says not accepted but I know a colleague has accepted the invite.

Any help/advise would be appreciated.

Thank you

Julia