Hi Patty
According to The Scots Peerage, vol. 2, p. 145, Sir Alexander Hepburne of Whitsome, married as his first wife, Elene Sinclair, widow of Sir John Mowbray (or Moubray) of Barnbougall, but there is no mention of her parents or other family.
No date for the marriage is given, but as her first husband died in 1518, it obviously had to be after that. Consequently her life effectively overlaps that of Helen Sinclair, wife of James Ogilvy, 4th Lord Ogilvy of Airlie, and they must be different women.
I also note that The Scots Peerage, states that Sir Alexander Hepburne, and Elizabeth Hepburn, wife to John Lundy are the children of Elene Sinclair, but that Patrick Hepburne, Robert Hepburne and Thomas Hepburn are illegitimate sons of Sir Alexander Hepburne of Whitsome.
Elene Sinclair the wife of Alexander Hepburne already has a profile on WikiTree but neither of her Hepburn children are connected.