This looks more like an archeological question than a question for a historian, but i will help you. If you want to know who these people were, the first place to search is usually the church. Churches were requiered to keep track of bautisms, deaths and marriages, with that you can check who "Grant" was, his family and usually where he lived, or the parents home. For the location of the mill, is usually easy, the closest house to the water source is the mill. also if there is little water, usually they made dam to raise water level and make the mechanism work. If you go to the river, we will see some points with an accumulation of rocks . those are probably the remains of the dam. If you need help, write to me and i will try to explain you the whole proccess of locating places. Sorry for the bad english