Hi
You don't give any details of their ages and whether they had any children etc so the following is general advice
Deaths up to the late 1940's /early 1950's are available on freebmd
www.freebmd.org.ukSome deaths are also available on
www.lancashirebmd.org.ukTheir childrens marriages can be looked for on the same websites
Births of children after 1911 can be found on freebmd by using surname O'Reilly and mothers maiden name Donnelly
More personalised info (eg) their actual lives after 1911 could only be obtained by tracking any living descendants
I can't see any children born to them up to 1930