I looked for birth registrations in Kanturk district for Fitzgerald surname and Lane mother's maiden surname. 18 results 1885-1920. Another search for Fitzgerald births with Law mother's maiden surname found 4 more. (Lane has been transcribed as Law on some registrations.)
There were 5 marriages with a Fitzgerald groom and Lane bride in that period.
Daniel Fitzgerald (farmer) & Mary Lane, marriage registered in Kanturk 1897, had some children with same names and similar ages to children of David & Margaret (John, Norah, Mary, Hannah, Katie, Ellen, Julia). They seem to be the family at House 6 Croanrea, Clonfert West on 1911 census.