Here is the Utah Supreme Court’s opinion in the Adoption of A.B. and D.T.

An excerpt:

In this case, the Nation’s original notice of appeal was defective. Even though it was filed within fifteen days of the adoption order and signed by the Nation’s counsel, the notice of appeal did not contain the Nation’s signature. And the Nation did not acquire the additional fifteen days to correct the deficiency because the Nation’s counsel did not file a certification of diligent search.

emphasis added