The correct answer is, refinance the first while it’s still beneficial to do that (or don’t – 5% 30-year fixed is quite good to begin with). Miss a payment on HELOC, then call them, inform them that you’re upside down, inform them that they’ll be wiped in the event of a foreclosure, and offer to settle for $5,000 cash.
Of course, this answer is not suitable to be printed in a real estate tips section of The Washington Post.