Please tell me how I get to send and receive meeting invites from people who
are not on the same network.  E.g. I get meeting invites from an outside
company and that request comes through as an email.  I actually then have to
go into my calender and add it as an appointment.  

How can I or them send it and receive it as a meeting request and accept and
it pops it into my calender  -----without sharing my calender?  Happy to
share my calender to show busy but not happy to share details...