We have the concept of other Grover Cleveland style non-consecutive terms for alternate presidents. However, I do not think there has been a discussion on a non-consecutive term for a First Lady. And it very clearly involves the concept of said First Lady being married to two different presidents in her lifetime upon their entry into the White House, or some other oddities in terms of divorce, marriage and potential remarriage. So your challenge is to have the First Lady serve twice, or more.