Looking for half sister born in 1979 or 1980

My father told me I have a half sister. She was born in 1979 or 1980, in either Marion or Hamilton County. Mother's maiden name was Sue Gummerson (Gumerson). Father is Richard Copeland. My Dad thinks there is a chance she was adopted by doctors but not positive. My Dad and Sue were both in their late teens at the time. If this could be you please send me a message. Thanks! Jerred