Import ms exchange calender to ical but stop interactions

hi. I Have exported and imported my work (MS Exchangel ) calendar To iCal On my iMac as a iCloud calender. So it them syncs to my iPhone. I cannot / do not want to sync it due to work security so all I wanted was a COPY on my iPhone. I have that - import worked fine. However overtime I delete a meeting from iCal on my iPhone with multiple invitees it sends cancelation messages to all of My work colleagues. I don't want the copy to do anything when I edit it. How can I stop it from sending the emails out? or alternatively stop it from importing the invitees. (Some of my conference calls have many many invitees) it's a bit embarrassing.