Maggi, sounds like your daughter is falling into 2 traps.
1) The dealer is potentially taking advantage of her situation, the dealer "buying her out" is not getting her anything chances are she would be better off paying the fees on the Kia or even better buying out the Kia.
2) If she is 17,000km over and wants to lease again she might want to double check her mileage estimates or she will fall into this same trap again. You did say buy, so I hope she is looking to buy and not lease the Mitsu.