re Duncan family of Rothesay

I am trying to trace my Duncan ancestors . My Grandmother was Margaret Boag Young Duncan b.23-3-1874 to John Duncan (stone quarrier) and Agnes Officer,they were married in Rothesay on 17-3-1871,they had 7 children, Agnes b.1871 Margaret b.1874, Charles b.1875,Elizabeth b.1880 John b.1881 William b.1883 James b.1889.John was the son of Charles Duncan and Ann Rattray Duncan m. 24.2.1842 in Rothesay.If anyone can gice me any info re this family it would be much appreciated