How to hide events in Google Calendar
Propably this could give you a hint:

we have 3 accounts:


company@gmail.com
buddy1@gmail.com
buddy2@gmail.com


buddy1 and buddy2 added company@gmail.com's calendar as an external calendar (granted by company@gmail.com)


buddy1 adds an event and sets it as "Private" &amp; "Available" --> company &amp; buddy2 see nothing!
buddy1 adds an event and sets it as "Private" &amp; "Busy" --> company &amp; buddy2 see the appointment but can't read it's title or content, buddy1 of course can see his own appointment!