If a child's Parents or grandparents were enrolled members of a federally recognized tribe it is possible for them and adoptive parents (if under 18); to obtain any and all information with in his/her adoption records pertaining to their Indian Ancestry.
If the adopted child meets the enrollment criteria for a federally recognized tribe (every tribe has different policy and blood quantum Requirements); then under ICWA law it is required that the adoptive parents be provided any and all necessary information to respect and honor that childs right to be enrolled with there tribe.
Or upon turning 18, even sealed adoptions are required to provide all indian information if the adopted child were to request it.
additionally, by law that child is also supposed to recieve legal assistance to obtain adoption information and/or membership that pertains to His/her
Tribe(s).
You could contact the
BIA office in
Phoenix Region. Sometimes, in the past they have held
Phoenix documents in Riverside,CA. However they have there own Agency in AZ.
They may not be able to provide you with what you are looking for right away, however, with patience and sometimes much needed persistence they can point you in the right direction or provide contacts of individuals and/or Indian Legal Services to help aid you in obtaining your documents/information.
If you know what tribe you are then you could contact that tribes administrative offices preferably the enrollment department or Cultural/Historical Preservation Program director or what ever department those types of things are in for that tribe. Many tribes have made efforts to document family trees, however the majority of Documentation is
Oral History.
Good
Luck! Hope you are able to find what it is you are looking for.