The GAL is allowing you to speak on your daughter's behalf?

Really? And the judge has approved this?

What does the GAL think about your limited-cognitive adult child having a child of her own? Was she actually legally capable of giving consent? Do you realize that this actually might give the father an edge with actually getting custody of the child himself?

All of this aside, the bottom line is that if Dad now wants to be Dad, the TPR is not going to happen.