GREENAWAY families of County Armagh & County Antrim, Related?

I'm attempting to tie my line of the GREENAWAY's from County Antrim to the GREENAWAY's from County Armagh.  

Through a Y-DNA test I've been linked to a D. GREENAWAY, (gentic distance between us of 2).  In speaking with him, that several years ago he visited Portadown and Tandragee, County Armagh where his family emigrated from.  From conversations there, he learned that all the GREENAWAY's in that area are related to each other.  My GREENAWAY family has been traced to the Parish of Magheragall, Townland of Mullaghcarton, County Antrim, approximately 20-25 miles from Portadown and Tandragee.    

D.GREENAWAY has traced his ancestry back to a NICHOLAS GREENAWAY (b. about 1819. Scarva, County Down).  NICHOLAS' son was GEORGE GREENAWAY (b. May 26, 1842, Tandragee, County Armagh/d. Ludlow, Massachusetts, USA, May 13, 1906).  GEORGE's children were: 1-JAMES GREENAWAY (b. Feb 21, 1873, Tandragee, County Armagh/d. May 1, 1928); 2)-ISABEL GREENAWAY (b. Dec 1, 1877, Ireland/d. Feb 17, 1948); 3-WILLIAM GREENAWAY (b. Jun 18, 1880/d.Jan 26, 1885); 4-MARGARET JANE GREENAWAY (b. Jan 1, 1883, Ireland/d. 1933); 5-GEORGE GREENAWAY (b. Nov 14, 1885/d. Nov 6, 1919); 6-DAVID EMERSON GREENAWAY (b. Jun 6, 1871, Tandragee, County Armagh/d. Dec 31, 1952).

My family has been traced back to the 1860's in County Antrim, Parish of Magheragall where I found a SARAH GREENAWAY listed in the Griffith Valuations in the townland of Mullaghcarton.  From the death certificate of my great-grandfather MICHAEL GREENAWAY (b. about 1835, Ireland/d. Apr 8, 1904, McKeesport, Pennsylvania, USA) his parents were listed as JAMES GREENAWAY and SARAH GREENAWAY (maiden name unknown).  I have found my great-grandfather MICHAEL had several siblings:  1-MARY GREENAWAY (b. About 1839, Knocknadona, County Antrim/d.1869/Married WILLIAM CARLISLE Apr 30, 1860, Lisburn); 2-CATHERINE GREENAWAY (b. About 1843, Lisburn, County Antrim, Ireland/d. Mar 30, 1898, Lisburn, County Antrim/Married NELSON DUNLAVEY Sep 30, 1865 at the time residing in Magheragall Parish); 3-WILLIAM GREENAWAY (b. About 1831, Ireland/d. Unknown/Married ANNE McDOWELL Nov 6, 1852, Lisburn).   

I also found a MICHAEL McGREENAWAY in the same 1860 Griffith Valuation in the Townland of Mullaghcarton as I found SARAH GREENAWAY.  Until this, I had never found the prefix "Mc" attached to the GREENAWAY name.  I bellieved this to be my great-grandfather, but doubt has been cast since he emigrated with his family to Cleator Moor, England sometime between 1864 to 1868 while revaluation records indicate that McGREENAWAY was listed as living in Mullaghcarton after those dates.  However, I have yet to find any death records for a MICHAEL McGREENAWAY.

Family legend has it that my great-grandfather MICHAEL GREENAWAY became Roman Catholic to marry my great-grandmother ESTHER BRENNAN and shunned by his family.  Yet I have found that his 2 sisters sons did come to live with him in the U.S.  ROBERT CARLYSLE was living with him according to the 1880 U.S. Census, and JOSEPH DUNLEAVY came to the U.S. in 1907.