I don't think that Mary Ann and Elizabeth were born in TN.I think that they were b. in SC.Here is the census data I have collected for the SC O'Barrs:
1790 Pendleton Dist. Robert OBar 133
Daniel Obar 101 George Reeves 121 Thompsey Obar 023 (possibly Daniel's mother?) William Nicholson 323
1800 Spartanburg Dist. Michael O'Barr10001 00100 Robert O'Barr10001 2201
1810 Pendleton Dist. Michael31100 10010 Robert 00001 12001
1820 Abbeville Co. Michael 111110 22010
1830 Anderson Co. Robert 1100100001 Wm. 10011 21001 Mary 00000 0001001
Abbeville borders Anderson Co and when the OPD broke up into Anderson and Pickens Dist. in 1827 it is possible that they took in some of Abbeville Co. down around Honea Path. I found this out researching Reuben Brock because some of his land was originally part of Abbeville and was later in Anderson Co.
In 1850 Leonard and Elizabeth O'Barr Hamilton were in Anderson Co.I believe that Mary O'Barr in 1830 was Mary Hammett O'Barr and that she was the widow of Michael in Abbeville in 1830. Michael was probably the s/o Robert s/o Daniel the immigrant.
Abbeville courthouse burned (not by Yankees) but the estate records were housed in a building across the street so they survived.I will try to see if there is anything on O'Barr in Abbeville or Anderson Co.
Second, there was no Walhalla until 1859. I have looked here for some record of Mary's death to no avail.Could she have been living with Mary's family?Or one of the sons that were in the Anderson census in 1830?I know that the Hamilton's apparently moved to the Walhalla area later.I'm not sure where the name of Daniel came from as the father of the girls but I think that is wrong and probably someone picked it up from the 1790 census.I will keep researching and see what I can find.