Matthew Mawhinney

I had a look at the 1831 census for Ballymacpeake and there are no Mawhinney households there. Likewise none in Griffiths Valuation for 1859. Nearest Mathew lived in Drumanee Upper on plot 7. He was the only Mathew Mawhinney in the parish, listed in Griffiths. This looks to be him in the 1901 census. He was Church of Ireland.

http://www.census.nationalarchives.ie/pages/1901/Londonderry/Bellaghy/Drumanee_Upper/1541331/

However by 1901 we also have this family who are in the right townland and of the right denomination:

http://www.census.nationalarchives.ie/pages/1901/Londonderry/Rocktown/Ballymacpeake_Upper/1542790/

The revaluation records indicate that Matthew arrived in Ballymacpeake in 1884. He initially had land on plots 27,28 & 29 but by 1901 he?s on plots 25a, b & c (which were some consolidated properties) and had a farmhouse, outbuildings and 5 acres.

http://www.proni.gov.uk/index/search_the_archives/val12b.htm

This is Mathew in 1911, apparently with a new wife, whom he apparently married 12 years previously (though that can?t be quite right). 10 children of whom 6 were still alive. Presumably that?s by both marriages.:

http://www.census.nationalarchives.ie/pages/1911/Londonderry/Rocktown/Ballymacpeake_Upper/609040/

The 1911 census gives a clue that one of the daughters has probably married a Campbell and is living in Scotland. (It was common to do this and to send some children back to the parents at home to make life easier).

Mathew?s marriage certificates should name his father. You say he was married to Margaret Ritchie. If you can trace that marriage then that should help you take the next step back.