This case has gone up a couple of times.
The child welfare case did not fall under ICWA because the child was not as a member or eligible for membership in the tribe, so the Court used the UCCJEA to determine jurisdiction.
Here is the opinion in Billie v. Stier:
This Petition for a Writ of Prohibition evolves out of a custody dispute between the mother, who is a member of the Miccosukee Tribe of Indians, and the father, who is not a member of the tribe of Native American heritage. The issue is whether the Miccosukee Tribal Court or the Circuit Court of the Eleventh Judicial Circuit has the jurisdiction to decide the custody dispute. The mother petitions for a writ prohibiting the Circuit Court from exercising jurisdiction over the custody matter. Based on the facts of this case and the Uniform Child Custody, Jurisdiction, and Enforcement Act (“UCCJEA”), we conclude that the Circuit Court was correct in determining that it, and not the Tribal Court, has jurisdiction to decide the custody issues and we therefore deny the petition.
Tribal court proceedings are now included in some instances. For example, under the UCCJEA, a state court will be required to treat tribes as if they were states and tribal court custody proceedings as if they were sister state court proceedings and to enforce tribal court custody orders.