Looking for Alexanders of Lisnagunague County Antrim Nth Ireland

My great-grandfather, DAVID ALEXANDER,born 10.03.1855,immigrated to N.Z in 1879. He was from the small village of Lisnagunague in County Antrim. (Near Bushmills.)His father was JOSEPH ALEXANDER 1807 - 1887.

JOSEPH ALEXANDER had 2 known siblings: Matthew and Matilda. I would like to know whether there were any others. I would be interested in any information at all regarding this family.