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I found the information below regarding Feighery on an Irish Times web site http://www.irishtimes.com/ancestor/surname/
Feighery:Quite numerous: Midlands etc. Ir. Ó Fiachra. MacLysaght says the name originated in Tyrone but it no longer appears there. Fiachra is a personal name which is known in France from St. Fiacre of Meaux who gave his name to the horse-drawn cab there.Ó Fiachra:Feighery, Feery: líon beag: Lár na Tíre. As Tír Eoghain dóibh ar dtús ach má's ann dóibh anois, is faoi Hunt atáid. Ciallaíonn an t-ainm Fiachra "rí catha". Bhí Fiachra N i Meaux na Fraince mar a dtugtar ómós dó mar éarlamh ar lucht taistil.
Here is a link to the online Irish phone book. http://www.eirphonebook.ie/# There are 11 Feighery records in Co. Offaly. Make sure you use the Residential Tab. They are mostly in Tullamore and Kilcormac.
Did any of the siblings stay in Ireland?