I have just received my father's record from UK. Here are his notes on the 'American Branch' as he researched
WILLIAM WYVILL of Frederick County, Maryland aged 15 on 14 1719 (GEC 'complete Baronetager') 1st son and heir of Darc'y Wyvill, Collector of Excise at Derby (d.there . 4 Jan1735, who was 2nd son of 4th Baronet, Sir William Wyvill, died circa.1684). Emigrated to America possibly as early as 1727. Lost at sea on a return voyage to England. Admon appears in Frederick County MD. in 1755. Probably married in Maryland. Estate divided between children: Jane (exec), Marmaduke (exec), William Edward Hale and three other girls.
Furthermore: It has been generally accepted that William's departure for America may have been before 1727. William's father D'arcy purchased an army commission for him as a Captain in COL. Wm. Breton's Regt. of Foot on 12 December 1711; the following year he went on half pay at the age of 5 years! His commission as a Captain in the 16th Foot (subsequently The Bedfordshire Regiment) was renewed by George II so it may have been after 1727 that William emigrated to America;
This seems to tie in with your information. I have a pedigree for 8 generations ending with Willie Juanita Wyvill NY b Washington DC 30th June 1923
I will be putting this info on-line shortly(time constraints)