Reilly/Riley/Henderson

Hello - I've recently discovered some ancestors who hail from Errironagh Townland, County Roscommon. Mary Reilly/Riley born around 1813 in Co. Roscommon married James Henderson from Do. Dublin at Ardcarne Parish Church of Ireland on 17 July 1844 (James Henderson's address at the time of the marriage was listed as Mohill). Their eldest daughter (my direct ancestor) Mary Ann Henderson was born 22 Nov 1845 and baptised in Ardcarne Parish Church on 11 Dec 1845. On her baptismal record, their address was listed as Errironagh. They probably emigrated to Canada around 1847 (based on her siblings place of birth) and are found in the Canadian census starting in 1851/2. I've been unable so far to trace Mary Reilly/Riley or James Henderson any further back. I'll be visiting Ardcarn parish, Co. Roscommon on my next trip to Ireland in December of this year, and would love to find out more about the family before my visit. Seeing where Mary lived growing up, and where Mary and James lived prior to emigrating to Canada would be incredible! Any help in my search for Mary's family would be greatly appreciated. Thanks so much! (JustSayItMD@gmail.com)