A tough life decision......

[shilala]

Another thought, just to throw it out there, and I don't have any way of knowing if it's something you guys would consider...
Buy your parent's home as an investment property. Rent it, lease it, or leave it sit if you can swing that. It's an enormous tax advantage and it'll leave the option to sell your current home wide open.
You won't need to produce any cash, you let the bank take a second on the equity in your current home as collateral.
When you buy the parent's home, claim it at twice what you paid for amoritization purposes, assuming you'll be doing tons of upgrades. That way if you ultimately sell it at a profit, you can still take a large capital gains loss and leave the game whistling.
There's obviously more to talk about so far as that route goes, but it would be one that keeps all your options open for years to come.
It may change your retirement portfolio a bit, but you won't realize the tax hit you'll get with the Roth and 401K in the end. Plus you'll save a fortune between now and retirement on taxes.
You'd have to crunch all the numbers, but it smells pretty sweet from here. It worked real well for me. I retired at 42, although mine was forced by my health. Fortunately I was prepared (enough).