Calendar entry using FYI

When my colleague creates a calendar entry, she fyi’s it to me. We send updates to each other and track the movements with comments. When she updates the entry to remove one invitee and add a new one she FYIs me but my calendar entry does not reflect the new Invitee list - is this a bug or is it meant to work like this?

Subject: Calendar entry using FYI

It’s designed to work like this.