On May 11, 1777 Silas Deane (1738-1789), American Commissioner to France, sent a letter to the French diplomat Conrad Alexandre Gérard (1729-1790) asking about the detention of Gustavus Conyngham and his men. Deane mentions the children of Conyngham in his letter. Subsequently, multiple historians also refer to the Conyngham children. Evidence for the existence of offspring from Captain Gustavus Conyngham and his wife Ann Hockley Conyngham (1857-1811) is lacking. A study of Gustavus Conyngham's Last Will and Testament reveals that he did not identify any of his own children in his will; however, the document can be interpreted as corroborating that he had two sisters as stated in Irish Pedigrees by O'Hart (1892). I have added a preprint of this project under the title The Last Will and Testament of Captain Gustavus Conyngham.