@IRonMaN   I already asked where they vote and didn't get an answer.  Knowing the politics of some of the people in those two states, I figured the answer was "both."  I don't know if either state requires a declaration of homestead, or allows a homeowner to have more than one.  My bet is that when they sell the Virginia house, they'll want to claim it was their principal residence two out of the last five.  But then, can half-years be counted for Section 121 purposes?