I don't know if this will help but have you tried looking in the Dawes Commission Allotment of the Five Civilize Tribes in Oklahoma. I can't remember if the Chickasaw's were one of those tribes but it could be a start. Also, if you have one of your family member's "roll numbers" (this is the way native Americans were identified in the Oklahoma territory if they were on the Dawes roll). If you have the roll number, records in Muskogee or Okmulgee, Ok might be useful. One of your ancestors might have put the roll number in a Bible or another place sacred to them. I found my family member's roll number in my grandmother's bible. For example, it might be B40 or something like that. Good luck.