If you Google "worse mac app of all time," you will get a million hits for PocketMac (the "Blackberry for Mac" app). My advice to you is to get your daughter to try it, but backup everything first! Address book and calendar especially, since they have the biggest issues. PocketMac works well for some folks, so she may luck out.

Also I would suggest she goes into iSync preferences and set it to notify of any changes to the desktop. That way when PM decides to delete or merge contacts, she can stop it before damage is done.

Other options include Missing Sync ($40), which is better than PM but has many of the same issues (as you will discover reading the various Blackberry/Mac message boards). Or your daughter can be patient and wait for RIM to release a desktop manager for Mac, which is rumored to be happening soon (word is that it is being beta tested by select testers now, but that is hearsay). The latest thought is that it will be available sometime around August, but I have no clue as to how accurate that statement is.