Q: Tenants in common transfer without a will

A: You will need to file a Termination of Decedent's Interest with the Register of Deeds for the county in which the property is located.

You may access the form and instructions at the WI Register of Deeds Association website on their forms page which is located at https://www.wrdaonline.org/forms

Alternatively you may retain an attorney to assist you through the process.

A: When a tenant in common passes, their interest in the property passes to that person's estate. If your Mom's brother passed away with no Will, he died what we call "intestate" therefore his property would pass according to the Wisconsin rules for intestate succession in Chapter 852 of the Wisconsin statutes. The property will past to his nearest living relatives, generally to the surviving spouse, and then to his children, if any, and then to the next nearest living relatives. You can find the full statute no intestate succession here https://docs.legis.wisconsin.gov/statutes/statutes/852

In terms of getting the property out of the deceased brother's name, I recommend consulting with a qualified real estate and probate attorney. It is likely that an heir of your Mother's brother can file the paperwork to open a probate estate on behalf of the brother, and take title to the property on behalf of the estate. If the interest in the property is worth less than $50,000 there may be a simplified probate process that can be pursued. Either way without a Will, or Trust, you will need to follow the Wisconsin rules for intestate succession for passing his interest in the property.