Generally speaking, insurance policies have designated beneficiaries which means the proceeds do not pass through the probate estate. The beneficiary must notify the insurer of the death of the insured to receive payment. The only reason for the insurance proceeds to pass through the probate estate is the death of the designated beneficiaries.
You should consider hiring an attorney to approach your sister for more information if she won't willing give it to you.
Adding the the previous correct answer; if the life insurance list your father's estate as the beneficiary a probate may be necessary. You should contact an estate planning attorney to discuss how to compell all information from your father's estate. Even if you don't need the probate, this may be the only way to find out what else is there.