Hello Ian, If your step-dad has any more information on his Ballymena relatives he'd be willing to share, it might help us discover some common connections. So many McAlonans are from the Ballymena/Ballymoney area, there must be shared ancestry somwhere.
My MacAlonans are descended from Thomas McAlonan (b. 1786) and Nancy Blair (b. 1789) mentioned as living in Ballycregagh Townland, Dunaghy parish, Co. Antrim in the 1851 census. Tom and Nancy had son James(b. 1819-20, daughter Margaret (who married a James Boyd Unclear, but possibly there was a daughter Mary (who married a McCleary) and a son John, b. cir. 1831.
My lineage is derived from the above mentioned James. James Mcalonan married Margaret. They had six children: Peggy Jane Margret)b. 1845; Elizabeth (Eliza or Lizzie)b. 1847; Thomas b. 1850; Thomas b. 1850; Matthew b. 1853; James b. 1853; and William Blair b. 1859. Thomas married a Margaret Patton (they are buried in Clough); Eliza married a Robert Templeton and had two children, Margaret Jane and Thomas (all are buried in Clough); Matthew moved to Detroit,MI as did Willaim Blair (they came to the US around 1885.) William Blair is my great-grandfather. He married Lizzie Caldwell McFetridge and sons William Torrens and Matthew Walter (my grandfather).
It goes on from there. Don't know if this helps find out if there is a relationship to your step-father's Joseph and Molly or Stephen and Carol.
If there is anything your step-dad knows about when, how and why so many McAlonans moved from Scotland to Antrim, Ireland, I'm sure there are lots of us who would like to know. And the farthest-back origins of the McALonan name? I have heard that they are a sept of the Clan Cameron originally from the Lochaber region of Scotland. There is supposedly a Glen "Lonan" near the village of Taymult I would like to hear about.
I've also read of an Irish relationship to the royal family of MacGiolla Fhinnein (follower of St. Finnian) and anglicized as MacAlinion. There is supposed to be a link with the Irish Leonards associated with West Ulster (Donegal and Fermanagh). They are descended from Giolla Finnein O'Muldory, whose head was chief or lord of Lough Erne.