You should look on www.familysearch.org
It appears your Daniel Devlin, son of Edward Devlin and Grace Doherty, had a few siblings.
There was a Denis Devlin born Feb. 19, 1868 in Clonmany, Co. Donegal.
There was a Grace Devlin born Nov, 11, 1870 in Clonmany, Co. Donegal.
There was a sister Mary Devlin who married Arthur Thompson, was born May 12, 1869(?)(probably 1859) in Co. Donegal, and she died June 27, 1931 in Chicago.
There was a sister Bridget Devlin who married William Lowen, and she died June 4, 1938 in Chicago.
Some of these Devlins are on http://www.findagrave.com/cgi-bin/fg.cgihttp://www.findagrave.com/cgi-bin/fg.cgi
This family is in the 1880 census in Lyons, Clinton Co., Iowa. Census taken June 1, 1880.
Edward Devlin, head, 45, laborer, born Ireland, father born Ireland, mother born Ireland
Grace Devlin, wife, 43, keeping house, IRE, IRE, IRE
Mary Devlin, dau, 20, servant, IRE, IRE, IRE
Daniel Devlin, son, 18, clerk, IRE, IRE, IRE
Bridget Devlin, dau, 15, servant, IRE, IRE, IRE
Dennis Devlin, son, 10, at school, IRE, IRE, IRE
Grace Devlin, dau, 8, at school, IRE, IRE, IRE
This census is on www.ancestry.com and the family surname is transcribed as Diblins.