Thanks Jimaintuit:

I failed to mention in my original question that the newly acquired property in the 1031 exchange is a investment residential rental property. So, if they add another residence to this property. Then it appears they would have to rent that property for 14 days or more and limit their personal  use to the greater of 14 days or 10% of the number of days during the 12-month period that the dweling unit is rented at a fair rental. Also, to meet the safe harbor rule they would need to do that for each of the 12 month periods immediately after the exchange.

Thanks again for your input.

JimD