Sorry for kidding earlier, but treat these words of advice seriously.
Based on what you said, foreclosure is on the horizon for them and you if you cosign. It would be cheaper for you and you'd save money by giving them the money so their mortgage payment gets lowered. If you gave them $40-$50k, or whatever it takes to bring them to a level they can afford, you would save on the amount of money you would have to pay if your were to get a mortgage in the future. If a forclosure happens, it'll cost you way more than $50k in extra interest and charges due to the forclosure on your report. They are better off selling and renting for a year or so until they can stop bleeding money.
