Merge Time Machine Backups

Hi!

My girlfriend recently got a new air with ML which we set up using a time machine backup of her old computer which was running snow leopard. We used migration assistant to clone her old computer onto the new one, but didn't know at the time to "Inherit Backup History." Now when we plug the external drive in, Time Machine backs everything up to a completely new grouping, essentially doubling the amount of space it takes on her drive (b/c it is a completely new image instead of recording just the deltas) and also makes it difficult to access older time machine snapshots.

Is there any way to combine the backups together without restoring from scratch, choosing "Inherit Backup History" and manually updating everything she's done since getting the new computer? The changes between the two versions is minimal but I'm not sure if time machine is smart enough to differentiate between the granular details.

I really want to fix this before she leaves overseas tomorrow. Any help is appreciated!