When siblings disagree about legal authority

Reviewed by a licensed elder law educator | Updated March 2026

Sibling conflict over who holds power of attorney or guardianship is common and often rooted in years of family dynamics rather than the documents themselves. The person named in the documents has the legal authority unless a court says otherwise. Resolving disagreements requires direct conversation, documentation, and sometimes mediation or legal intervention.

The Documents Decide, Not the Family Argument

Your mother had a stroke. She's in the hospital. Your brother called and said he'd been named as healthcare power of attorney and was going to make decisions about her medical care. You were shocked. You're the one who's been helping her with medical appointments. You're the one who knows her values. You thought you'd be the one making decisions. But you can't. Your brother has the legal authority, and you don't.

Or the reverse: your father signed documents naming you as his financial power of attorney. Your sister is furious. She says you're going to cheat your parents and take their money. She's threatening to go to court to challenge the power of attorney. She's telling other family members not to trust you. You're not trying to cheat anyone. Your father chose you because you're the one with financial expertise. But now you're dealing with family conflict on top of managing your parent's affairs.

According to the AARP, family disputes over caregiving roles and legal authority are one of the most common sources of conflict among adult siblings. The ABA notes that contested guardianship and power of attorney challenges make up a significant portion of elder law litigation in probate courts. These disputes rarely come out of nowhere. They surface old grievances, perceived favoritism, and different ideas about what a parent would want.

Legal authority comes from documents. If you're the healthcare power of attorney, you have authority over medical decisions because the documents say so. If your sibling is the financial power of attorney, they have authority over finances because the documents say so. The person named has legal authority and is legally responsible for acting in your parent's best interest. If another person thinks the named person is not acting appropriately, they have recourse through the courts. They can petition for investigation, removal, or appointment of a guardian instead. But the person named in the documents holds the authority unless and until a court removes them.

This means that if your sibling is the healthcare power of attorney, they get to make medical decisions. If you disagree, you can ask them to reconsider, suggest alternatives, or ask the doctor to discuss options with the family. But your sibling has the authority. If you believe your sibling is making decisions that actively harm your parent or serve their own interest rather than your parent's, going to court is an option. But it's expensive, adversarial, and usually the last resort.

Working Through It

If you're the sibling without authority and you disagree with decisions being made, you have options short of court. You can ask your parent to update the documents to give you more authority or a collaborative role. If your parent still has capacity, they can create new documents that change how authority is structured. But your parent has to agree.

You can ask your sibling to be more collaborative. Many families work out an arrangement where the named person has the legal authority but decisions are discussed with input from other family members. This isn't legally required, but many families do it, and it reduces conflict. You can ask that healthcare providers or financial institutions involve multiple family members in meetings. This doesn't change who has legal authority, but it allows for input.

If you think your sibling is acting in their own interest rather than your parent's, you can ask for accounting. A financial power of attorney is required to keep records and can be asked to account for how they spent money. A healthcare power of attorney should be following your parent's wishes. If they're not, and if your parent still has capacity, your parent can object directly. If your sibling is truly misusing authority, court involvement may be necessary. This requires an attorney and involves petitioning the court to investigate. It's expensive and puts your family through a legal proceeding, but if your parent is being harmed, it may be the right thing to do.

If you're the sibling with authority and another sibling is questioning your decisions, document everything. Keep records of financial decisions. Note your reasoning for medical decisions. Explain your thinking when asked. You have legal responsibility to act in your parent's best interest, and documentation protects you. You can also invite collaboration. Even though you have the legal authority, involving siblings in conversations reduces conflict and demonstrates that you're acting transparently.

If you're the parent making these decisions about who gets authority, you can prevent some of this conflict by being clear. If you name one child as healthcare power of attorney and another as financial power of attorney, make sure they both understand the arrangement. If you want decisions made collaboratively, say so in the document. If you name one person as primary and another as backup, be clear about what that means. Having clear documents and open conversations about why you chose who you chose reduces the chances of conflict later.

Taking Steps to Resolve It

Try direct conversation first. Don't go to other family members. Don't try to undermine the other sibling. Talk directly. "I know you're the healthcare power of attorney. I'm concerned about some of the decisions being made. Can we talk about what you're thinking?"

Listen. Your sibling may have information you don't. They may explain reasoning that makes sense once you hear it. Or you may still disagree. But having the conversation matters.

If direct conversation doesn't work, consider involving a neutral person. Some families involve their parent's physician or a financial advisor to discuss decisions with everyone present. A neutral third party can bridge disagreements that feel impossible between siblings. Formal mediation is another option. Some elder law attorneys offer mediation services specifically for family disputes around caregiving and legal authority. This is less expensive and less adversarial than going to court.

If you think your sibling is misusing authority, consult with an attorney. An attorney can advise you on whether you have grounds for court involvement. But be realistic about what court involvement means: cost, time, public records, and a legal proceeding that your family has to live with afterward.

If your parent has already lost capacity and siblings are in conflict, court involvement may be the only resolution. This is exactly why having clear documents that reflect your parent's wishes, completed while they still had capacity, matters so much. The documents provide guidance about what your parent wanted, which can help resolve conflicts even when the family can't agree.

Most families work through these disagreements, even if it's painful. The key is not letting the conflict prevent your parent from getting the care they need. Your parent still needs help. Whether the authority is held by one sibling or shared, the goal is your parent's wellbeing.

Frequently Asked Questions

Can my parent name co-agents on a power of attorney?
Yes. Your parent can name two people as co-agents who share authority and must act together. They can also name one person as primary agent and another as successor who takes over if the primary can't serve. Co-agent arrangements can reduce sibling conflict but also create problems if the co-agents disagree. An attorney can help structure this based on your family's dynamics.

Can I challenge a power of attorney I think was signed under undue influence?
Yes. If you believe your parent was pressured, coerced, or manipulated into signing a power of attorney, you can petition the court to invalidate it. You'll need evidence, typically from witnesses, medical records, or expert testimony about your parent's cognitive state and the circumstances surrounding the signing. An elder law attorney can evaluate whether you have a viable case.

What if the named power of attorney is not acting in my parent's best interest?
You can petition the court to investigate. Courts have authority to review how an agent is exercising power of attorney and can remove them if they find misuse, self-dealing, or neglect. The ABA recommends documenting specific concerns, including financial records and medical decisions, before pursuing legal action.

Should our parent tell us why they chose who they chose?
The ABA and family mediators consistently recommend that parents have open conversations with their children about why they made the choices they did. Understanding the reasoning behind the decision, even if you disagree with it, reduces the likelihood of conflict and legal challenges later. Secrecy breeds suspicion.

What if one sibling lives close and the other lives far away?
Geography often plays a role in who your parent names. The sibling who lives nearby may be better positioned for day-to-day healthcare decisions. The sibling with financial expertise may be better for financial management regardless of distance. Your parent can split authority based on each child's strengths and proximity. Many families make this work with clear communication and regular updates.

Is mediation a real option for sibling disputes about elder care?
Yes. Elder care mediation is a growing field. Mediators who specialize in family caregiving disputes can help siblings reach agreements about care decisions, financial management, and legal authority without going to court. The National Academy of Elder Law Attorneys and many state bar associations maintain directories of elder mediation services.