Hello, I'm also tangled up in this area. I can't find anything to verify that John Thomas Maxwell (1645-1681) is the father of Eustace. However, the Robert Maxwell 4th Earl of Nithsdale /Elspeth Sanders lead is a dead end. Because the dates listed for him as Eustace's parents were 1620-1667. Per two sources (see below) Robert Maxwell (1620-1667) was the 2nd Earl of Nithsdale. The title was created for his father (Robert Maxwell, the 10th Lord Maxwell and 1st Lord of Nithsdale). The book of Carlaverlok (page 382) by Fraser says this Robert did not marry; had no children and that he was succeeded by his kinsman and nearest male heir, John Maxwell 7th Lord of Herries. The 4th Earl of Nithsdale is a Robert Maxwell was 1627-1683 acc. to The Book of Carlaverlok. He married Lucie Douglas. He had a son, William, and daughter Mary. I'm in the Rev. Thomas Maxwell lineage. Sources: https://en.wikipedia.org/wiki/Robert_Maxwell,_1st_Earl_of_Nithsdale The Book of Carlaverlok by Sir William Fraser