Margaret Beaufort did not have a brother named Richard Wells who was killed by Edward IV. She had a brother named John Wells whose father was killed at the battle of Towton, but her brother lived until the reign of her son Henry VII and married Elizabeth of York's sister Cecily.
Jacquetta Woodville tells her daughter Elizabeth that the Beaufort family are in mourning for their kinsman Wells. Richard Wells (who was fictional) and Margaret Beaufort had different fathers so he (and any of the real Wells children Lady Beauchamps had) had no blood claim to Margarets paternal family.