Detailed answer — step‑by‑step under South Dakota law

1. Confirm where the estate is filed and who is the applicant

Find the probate case in the circuit court for the county where the decedent lived. The court file will show the application or petition for letters, the notice sent to interested persons, and any hearing date. If you did not receive notice, check the court clerk’s file and the application to confirm the applicant’s name and proposed bond amount.

2. Check whether you are an “interested person” and have standing

To object you must be an “interested person” under South Dakota probate law. That generally includes heirs, beneficiaries, creditors, or other persons who have a legal or financial interest in the estate. If you are an heir or a named beneficiary, you almost always have standing to object to a proposed appointment.

3. Common legal grounds to challenge an appointment

• Priority rules: South Dakota law establishes which relatives have priority for appointment. If someone with higher priority (for example a surviving spouse or another heir) wants appointment, the court may deny the sibling’s application.
• Not qualified to serve: the applicant may be ineligible as a matter of law (for example, a nonresident without permission, a convicted felon for certain offenses, or legally incompetent).
• Conflict of interest or breach of fiduciary duty risk: facts showing the applicant would likely misuse estate assets, has a history of mismanagement, or has engaged in self‑dealing.
• Undue influence or impropriety in obtaining a will (if a will exists) or in the application for appointment.
• Failure or refusal to post the required bond or provide required paperwork to the court.
• Criminal conduct or substance abuse that would prevent proper administration.

4. File a written objection (contest) with the probate court

File a written objection or answer in the probate case listing (a) your identity and relation to the decedent, (b) that you are an interested person, (c) the specific grounds for contesting the appointment, and (d) the relief you request (for example, denial of letters to the sibling and appointment of an alternate personal representative or ordering a bond). Sign and date the objection and follow the court’s local filing rules.

5. Serve the objection and request a hearing

Serve the applicant, other interested persons, and the court clerk with your objection according to South Dakota court rules. Ask the court to set a hearing on the appointment so you can present evidence. If the court already issued letters, you can still ask the court to suspend or remove the personal representative for cause (see next step).

6. Ask for immediate interim relief if needed

If you believe your sibling is likely to dissipate estate assets or take actions that would cause irreparable harm, ask the court for emergency relief: a temporary restraining order, an order to require the applicant to post a higher bond, or an order preventing the applicant from accessing bank accounts until the dispute is resolved.

7. Prepare evidence and be ready for the hearing

Bring documentary evidence and witnesses to the hearing. Useful evidence includes: the decedent’s will (if any), death certificate, proof of kinship or beneficiary status, bank statements, communications showing undue influence or mismanagement, criminal records, medical records showing incapacity, and affidavits from witnesses. The court will weigh credibility and legal priority rules when deciding who should serve.

8. If letters were already issued — removal and accountings

If the court already issued letters, you can still petition for removal of the personal representative for cause (misconduct, failure to perform duties, conflict of interest, incapacity). You can also request an accounting of estate transactions and seek restitution if funds were misused.

9. Consider settlement or mediation

Probate disputes often settle. Mediation can be faster and less expensive than a contested hearing. Courts may encourage or order alternative dispute resolution to resolve conflicts among heirs.

Statutory references and where to look

South Dakota’s probate rules and the Uniform Probate Code provisions are in Title 29A of the South Dakota Codified Laws. For the text of the statutes and rules that govern appointment, priority, bonds, and removal of personal representatives, see the South Dakota legislative website: South Dakota Codified Laws (search Title 29A). For procedural rules and local forms, check the South Dakota Unified Judicial System: ujs.sd.gov.

Helpful hints — practical checklist and tips

• Act quickly. Probate appointments and distributions can move fast; missing a deadline or hearing can limit your ability to challenge.
• Obtain the court file. Visit the clerk’s office where the estate was opened and get copies of the application, any notices, and the docket entries.
• Document concerns. Gather emails, texts, bank records, and witness statements that show why your sibling should not be appointed.
• Confirm priority. Verify whether you or another relative has greater statutory priority to serve; courts often follow statutory priority unless there is good cause not to.
• Prepare for bond issues. If concerned about misuse, ask the court to require a bond or increase the bond amount to protect estate assets.
• Consider a narrow, clear objection. Courts respond better to focused, factual objections (e.g., “applicant is a convicted felon and therefore ineligible”) than to general accusations without proof.
• Use court forms and follow local rules. Each county may have local filing requirements and forms for probate contests — check the circuit court clerk or the South Dakota Unified Judicial System site.
• Think about mediation. If family relationships are important, suggest mediation early to avoid costly litigation.