When importing contacts into its or a MacBook, what exactly happens when you use the update feature? Is all the data for the specified contact updated, or is the data merged, with any fields of the new overwriting the old, or ??? If I have a vCard with a contacts phone number and address, and choose to update that contact in my address book, and the one in my address book has a picture, will I loose my picture? There must be some rules to what exactly happens in an update???