William Crossett, Coolshinney, had brother-in-law James Crossett in 1911

[Peggy13]

William Crossett was born between 1845-1850 in Coolshinney, Co. Derry, father Richard, as per William's marriage to Matilda Watters in 1877 in Lecumphur.
https://www.rootschat.com/links/01scl/
In 1907, William and Matilda's daughter Annie Mary (baptised as Mary Ann June 2, 1879) born in Ballymuckleheany, died Nov 9, 1907 in Coolshinney. Her obit lists an uncle James Crossett and an uncle Doctor Crossett. My problem is that in 1911, the census has William and Matilda on it, with a brother-in-law James Crossett age 73, single. So, a brother-in-law means that James either married a sibling of William's or a sibling of Matilda's.  I can't find such a marriage. And if James married a sibling, how can he be single in 1911? Am I missing something? thanks for any help. Peggy
http://www.census.nationalarchives.ie/pages/1911/Londonderry/Ballymoghan/Coolshinny/612803/

[CaroleW]

Didn't you look for James in 1901?  Shown as not married.  Suspect it's just an error.  His entry is below Matilda's so shown as brother in law instead of brother to head of household

James is only 52 in 1901??

[Peggy13]

My opinion was that brother-in-law was an error but in case I was not thinking correctly, I posted the question. Thanks CaroleW.