Prayers for her, and that her biomom will one day see the truth of the Faith.

I agree with Jon, she did not intend to do wrong, and she did have an obligation to be obedient to her mother. I would simply explain that to us as Catholics the second baptism had no effect, and encourage her in knowing that she is still a Catholic.

My last posting mentioned confession for those who come back to the Church as adults, and in that case it would be to confess any sins committed after they abandoned the Faith.