I would suggest the activities of antiquarians and genealogists would be the reason for re-use of Greetham. Shades of Tess of the D'Urbevilles. A.W.Moore was anxious to connect himself to English Gentry and did some questionable things in his family tree - Stowell's life of Bishop Wilson said that the Moores had lived in Douglas time out of mind but AW chose to ignore his own family bible entries and attach his tree to another line. He was writing his "Old Manx Families" about 1889 but beware of possible quirks and quiddities.