Just a few newspaper mentions.
Coleraine Chronicle, 30 December 1905:
MAGHERAFELT BOARD OF GUARDIANS.
The Local Government Board wrote relative to the application on behalf of Arthur Grimes for the custody of his nephew, an inmate of the workhouse, and requested to be informed of the age of the boy, and whether he was an orphan or deserted child. Mr. Cauley said that the clergyman in Draperstown was not satisfied as to the uncle's ability to keep the child and would not give him a certificate, and the Clerk was directed to inform the Local Government Board that the conditions laid down by the Guardians as to the boy going out were not fulfilled.Mid Ulster Mail 10 July 1909:
A BOY DISCHARGED. A letter of recommendation was received from the Rev. Father Kerlin, C.C., that Arthur Grimes of Boveagh, would prove a proper guardian for his nephew, Andrew Kearns, who was an inmate of the workhouse. He was a wise and sober man, and would set Kearns a good example. As he lived in the next townland to Grimes he would look after the interests of the boy while there. It was resolved to give the boy to Grimes. Messrs Glover & McGuckin to prepare the necessary adoption form.Mid Ulster Mail, 15 July 1911:
SALES BY AUCTION.
MONDAY, 31st July, at 12 o'clock, Noon, for Mr Arthur Grimes, Boveagh, who is emigrating - 3 Acres of Corn, 2 Acres of Potatoes, etc.I also noticed the following two baptisms, see what you think.
Lissan RC parish, 29 June 1867, Sarah Jane of Charles McKearnan? & Eleanor Devlin, the word illegitimate is clearly there and I think the location after that might be meant as Muntober:
https://registers.nli.ie/registers/vtls000632605#page/61/mode/1up (right page)
Muntober:
https://www.townlands.ie/tyrone/dungannon-upper/kildress/oritor/muntober/Desertcreight RC parish, 4 December 1863, Arthur of Arthur Grimes and Ellen Devlin:
https://registers.nli.ie/registers/vtls000632534?locale=en#page/18/mode/1up (right page, top)
So if these are relevant, I suppose one possible scenario is that Sarah and Arthur were half siblings. I couldn't find a marriage for Ellen and Arthur, nor one for Ellen and a "Keela".