Can my husband's sister use her power of attorney for my son?

Full question:

My husband appointed myself and his sister as power of attorney while he was deployed overseas for 10 months. His eldest son is 15 (from a previous marriage) and lives with my husband's parents. I was told that my sister in law was given power of attorney because she takes care of his finances (the 15 year old). Problem is, she has now started to use it to sign things using my husbands name with her POA about my son who is 9 months old. My husband is total supporting his sister, i am assuming because he doesnt want to rock the boat with her because she takes care of his eldest son's affairs. I have told him how i feel and he says i am being rediculous and he doesnt care what his sister does and can sign whatever she wants. I have a huge problem with this. How do i put an end to this and can she legally do this? I dont need her signing things for my son! she doesnt even see him. what can i do?

• Category: Power of Attorney
• Date: 04/07/2025
• State: Missouri

Answer:

In this situation, the legality of your sister-in-law's actions depends on the specific terms of the power of attorney (POA) your husband created. It's crucial to determine whether both you and his sister must act together or if either of you can act independently. This should be clearly stated in the POA document.

Generally, a power of attorney can only be revoked or modified by the principal (your husband). However, if your sister-in-law is acting outside her authority or breaching her fiduciary duty, you may have grounds to petition the court for relief. This could involve seeking an injunction, which is a court order that requires her to stop certain actions. To obtain an injunction, you typically must show:

1. You have a strong likelihood of success on the merits of your case.
2. You would suffer irreparable harm without the injunction.
3. The injunction would not cause substantial harm to others.
4. The public interest would be served by issuing the injunction.

Fiduciaries, like your sister-in-law, have a duty of loyalty and care. They must act in the best interest of the principal and avoid conflicts of interest. If she misuses her authority, you may petition for an accounting or seek her removal as attorney-in-fact. If you believe she is breaching her fiduciary duty, you may have a viable claim against her.

In Missouri, where this situation appears to be based on the statutes provided, a principal can appoint multiple attorneys-in-fact, and their authority can be joint or several (Mo. Stat. § 404.707). If you believe her actions are inappropriate, consider consulting with an attorney who can help you navigate this situation and protect your son's interests.