Cahill - Ballynabanoge

[Franlynch]

This is for a friend of mine who has sight difficulties and doesn't use interent, hope someone can help.
her grandfather Cornelius Cahill, 1881, is on 1911 census with wife Mary and children Michael (10), Jeremiah (, James (6), Johannah (4), Patrick (3) and Cornelius - age blank.
the census shows they were living in ballynabanoge at the time and married for 11 years.  her father, John Cahill, was born in 1917.  this is all that is known of the family.
what would be the best way to proceed in finding out what became of the family.  all i know is that John went to the UK about 1940 but my friend would love to find out the whereabouts of the rest of the family if anyone has any ideas.  she believes that they moved to Croom.