You might try and contact the National Archives in Tx. and
request a copy of the actual enrollment card no. for your relative in question. This enrollment card should have parents listed on it as well as any siblings. It has their degree of Indian blood, Tribe enrollment town, parents, etc. I did this several years ago for several of my family members, Baker, Gentry and Hambys that are on the Dawes Roll. A lot of info can be obtained from these Roll Cards.
Barbara