Hi J.A.
Here is Darby's passenger list entry...
Ship "Scythia" departing Cobh (Queenstown) 21st November 1926, arriving New York 29th November 1926
Martin Mills age 27 and Darby Mills age 32, both born Ballina, Ireland
Father, Darby Mills, Barnathra, Bellina, Mayo
Going to, Cousin, Mrs B Broderick, 230 E 42nd Sreet, New York
Neither have been in the US before and they intend to stay "Permt."
Haven't found him in 1930 but will have another look
Agnes