Richard A. Parker appears to be Richard Anderson Parker, the grandson of Richard Andrew Jackson Harris. According to a family tree on ancestry, RAJH was born in 1832, and thus could not be the 15 year old musician we are looking for. Here is an excerpt from the Harris family history found on ancestry:
Story from Maggie, daughter of Rutha Jane Harris.
R.A.J. Harris and Elizabeth Waters eloped because one of their families was opposed to the marriage. The couple's oldest 3 children were born in Alabama. The family moved from Alabama to Texas between 1858 and 1861. Their youngest child was born in Texas. R.A.J. was a Confederate soldier in the Civil War and was killed on his way home. [He may have been on medical furlough after being hospitalized in Holly Springs, MS in October 1862; or, it could have been at the end of the war]. His granddaughter, Maggie, thought R.A.J may have been killed because some one wanted his horse. Maggie said that Elizabetht learned of her husband's death when someone came to the house and told her. Elizabeth died "not long" after R.A.J. was killed. The orphaned children lived with their Harris grandparents on a plantation somewhere in East Texas. After the grandparents died, the children lived with a Harris uncle somewhere in Texas. An attorney representing the Waters family came to take the orphans to live with their Waters'relatives. The children were not in agreement; so, they did not go with him to their mother's family.
When Margaret Harris married Ben Parker, it was with the understanding that her siblings could live with them until they married. [The earliest census record that I have been able to locate for any member of this family is 1880. The unmarried children were in fact living with Margaret and Ben Parker.]