The mother's sister was driving under the influence and ran a stop sign colliding with a bus. The father wants to file a claim against her insurance company for injuries his daughter sustained, but the mother doesn't want to because her sister was the driver. What are the father's rights at this point?

The father can do what he likes.
The father's rights are absolute.

So long as he as legal custody he can file. Why is it a problem to recover for injuries ?