John Cotter and Margaret Hickson

John Cotter married Margaret(Peg) Hickson in Kilmichael Parish in 1826.I cannot find any record of who she was.They had 9 Children,8 of whom emigrated to the US.I am the G Grand Daughter of the one son that stayed at home,Cornelius.Family anecdotes suggest she was the Landlords sister or daughter.In the baptismal records for Kilmichael,no Hickson was a Godparent for any of their children,it appears that The Hicksons were not too pleased about the marriage to one of their temants.
In the Griffiths Valuation records of 1852 a John Hickson apprears as a Landlord to the said John Cotter,Shanacashel,Kilmichael Co Cork .I have tried to find out who these Hicksons were and where Margaret came from.A cousin seems to think that they were from Dingle in Kerry but I can find no link to them,nor any birth record for a Margaret Hickson.She was probably born around 1800.If there is anybody out there who can help me I would be very grateful.