3 Hartless/ Clark m's, (1798-1894) Rockbridge, Va.

I am researching Clark family. My direct anc. is Nelly Clark, thatm. John Painter abt 1816 Amherst Co. Va.Nelly had 9 other siblings.Three of whom m. a Hartless.They are:
Jane Clark m. Henry Hartless 06/25/1798 in Amherst Co Va.
John Clark m. Mary Hartless 03/10/1804 in Rockbridge Co.Va.
Mary Clark m. John Hartless 1804 in Rockbridge Co. Va.
At least "one" of the Hartless families moved to Ohio, (Ross Co.) with my John & Nelly (Clark) Painter in 1822, (among others in the family) and again they moved together to Greene Co. Illinois in the early 1840's. There they remained.
Does any one have any information on either the Hartless, Clark or Painter families, can anyone identify the Hartless's as being siblings or would they be cousins?
Thank you for any help, it would be greatly appreciated.
Carol