iCal multiple user setup...

My girlfriend and I are just setting up iCal, so we can (finally) start to coordinate things a little better.

We each have a bunch of calendars, but now we also have a CalDav (gmail) shared calendar, where we write stuff in we plan to do together - like going out to friends, movies whatever...

My question is: When I write an event into this shared calendar, is there any feature that could let me know when my girlfriend has seen it? Like a checkmark box or something? It works well with the "invite to event", but since we share the calendar this creates a bunch of dublicates...

Also; if I work late one night, I write this into the shared calendar, so she will know about it. But, this event is also in my own "WORK"-calendar, thus, creating dublicates again. Is there any way to have A SINGLE EVENT appear on two calendars WITHOUT POSTING DUPLICATES??

Any help appreciated - or ideas how to set this calendar-stuff up. I am realising now that is not as easy done as I first thought

 

Anyone, plz?

Or if someone using iCal a lot could just explain how you go about getting events confirmed by someone else?