There could be a direct tie to this family from his son's,
the 101 of the research would be where your family was between 1900 and 1910.The first place to look is the Dawes list,(abt.1907)there were abt 21 Pitchlynn,8-9 males (sorry no Robert)Choctaw rolls--one family Chickasaw--at that time most would still be in Ok and received land.There was one Full blood family who also took his name--when they went to school and in this case the 1850's-they were required to drop their Indian name and take a English/Christian name-assigned or by choice and to learn to read and write. Indian name's are like "Nick" names.
The 1900 & 1910 Indian census also.
They also had slave's-(Freedomen) The site I used was the one I posted on this site--1860 Slave Index--Unionist slave holder
It gives all the Dawes list by name at a glance all tribes.
Good luck--Duck and Beaver fan-from-Coquille Ore.