Legal Question in Family Law in California

The only way to be sure that neither parent obtains custody of the nieces is to obtain a guardianship. Assuming that the children are doing well in your custody you have an excellent chance to be appointed their guardian.

Neither a Power of Attorney not a Notary Public will help you. You misunderstand those terms. They have nothing to do with the issues you are facing. A Power of Attorney is authority given by one person to another person to do things as if they were the first person. The nieces parents could give you a Power of Attorney to make health care decisions for the nieces in an emergency, for example. It is for a specific purpose, and is no substitute for a guardianship. A Notary Public is a person, not something you can get. Notaries are trained and authorized to verify the identity of people signing documents to assure that the person whose name is on the document is really the person signing it.