Found this on 1881 census
there is a Robert Stewart residing at 21 Benquhat, Dalmellington, Ayr.
He is a 37 year old Iron miner, born in Beith.
Living with him are his wife Margaret age 37 born in Dalry, Ayr.
also their children John age 13 born Beith, Peter age 11 born Beith , Jessie age 8 born Beith, Archibald age 6 born in Beith, Robert age 4 born in Galston, Elizabeth age 1 born in Dalmellington, 2 boarders also living with them.
if you think theses are yours, I will send you the full details