Thornhill Side

My Grandma Tingle (my dad's mom) maiden name is Thornhill. And I have hit a brick wall when it comes to her mom's parents. If I am reading it correctly there last name should have been Sublett but beyond that I find nothing. I am thinking a trip to Frankfort to access the birth records maybe in order. I just don't know where else to turn I am hoping by doing that I am able to see her parents name spelled correctly because the death record for her mom isn't very readable. Grandma passed away in 1988 but I do at least have the right names for her parents. I do know by 1880 her grandma was a widow who lived in Breckenridge KY so that is something I suppose but I don't have her year of death or even the actual date of birth. I do know it should have been around 1850 that she was born but I am not sure of her maiden name so that is a also problem. I know her grandpa name was William but beyond that nothing. That is one part that I don't enjoy is hitting these brick walls but with that being said I do love a puzzle and it is a big puzzle to figure out so I won't give up I will just keep trying and I will enjoy the hunt as I go. :-)  If anyone reading this has any information to give me regarding Milton or Maggie Thornhill parents names date of birth or date of death I would greatly appreciate any information you can give to me.