Margaret MANNY? 
What is the basis for "Manny" being the surname of Margaret, Countess of Norfolk, a predecessor to this Thomas, Earl and later Duke of same? Click the link and go to the article ON this predecessor Margaret, and the word "Manny" can't be found there. The only noteworthy and historical Margaret Manny that Google knows is Wikipedia's flag-seamstress active in North America in the revolutionary 1770's. As Jon Lovitz might say, "So, that would be later".2604:2000:C6AA:B400:7456:5EE0:243F:BF4C  Christopher L. Simpson