Thanks Dennis. I intend to give your website a thorough look. Since I posted my original question, I found this, which is a good argument for the identity of Elizabeth, second wife of Thomas Covington:
""A posting by Kathy Duncan on genealogy.com's Kavanaugh family forum explains the evidence for Thomas Covington marrying Elizabeth, sister to Jael Kavanaugh:
"By 1754 Jael (Cavanaugh) Covington, wife of Thomas, was deceased because Thomas and his new wife Elizabeth sold a little over 1000 acres of land that year. In 1759 Thomas Covington receives a legacy from the estate of Philemon Cavanaugh Sr. No mention is made of Elizabeth in that settlement. Keep in mind that Thomas could either be collecting on behalf of his daughters by Jael or in right of his wife Elizabeth. The settlement does not make it clear which. However, wtih that being said, Elizabeth Covington (without a husband acting for her) received a legacy from Philemon Cavanaugh Sr.'s estate on 20 Oct 1752." ""