Brothertons in Kilgarriff

My ancestor Robert Brotherton (b. 1796) and his wife Anne (b. 1799) were born in Ireland along with their 9 children.  Robert and Anne and 7 of the 9 children came to the United States in 1846 on the Ship Ocean.  The other two children followed about a year later.  I have the names of all of the children if needed and the dates of their birth. 

I searched the Griffiths Valuation Survey and found a James Brotherton at Townland: Tawnies Upper/t/clonakilty/old Chapel-La. (Parish Kilgarriff)  I also found a Robert Brotherton at Knockskagh (Parish Kilgarriff).  I understand that the Valuation Survey was between the years 1847 and 1864.  My Robert Brotherton came to the USA in 1846.

Is there a recommendation on how to determine if my Robert Brotherton family came from one of the Brotherton families in Cork?  I have also found a few more Brotherton families in other parts of Irelend through the Census documents but only these in the Griffiths Valuation.  Both of these Brotherton families appear to have been Tennants in the Griffriths and not the property owners. 

An associated question would be who would have been responsible to pay the taxes based on the Griffiths?  Would it have been the Tennant or the Owner of the land?  

Robert Brotherton - Dunedin, Florida