Trying to find my Grandmother

I had someone get in touch with me the other day but they had the wrong people, I wantMary born 1861 to Daniel Collins and Hanora Cotter. Mary came to Aust between and was Married to my grandfather in 1881 in Mt Barker Sth Aust. Don't know how many children there were but one of my uncles was said to be maned after her brother Dennis.

By her wedding certificate her father was  there address Mt Barker , but I haven't found any death notices for him anywhere in Aust, so presume he went back to Ireland, as one of my cousins  told me that her Mum went back to Enland about 1908 - 1912. Presumably to settle family matters. 

This is something I feel the need to clear up as I can't seem to let it be