estate Tax problems

My wives parents died 3 years ago. They lived in California, but they owned two homes in Wisconsin that were inherited. None of the family members involved are residents of Wisconsin. They live in California, Arizona, and Nevada. My sister-in-law probated the California estate(she is not a lawyer) according to a will. She had a Wisconsin layer doing a separate probate for the property in Wisconsin-- the same layer that created her parents will many years ago. Her parents choose this lawyer because he helped transfer the Winsconsin properties when her gradmother died many years ago.

Probate has taken a very long time and we feel she is getting over her head. The California probate is basically done and we are waiting for Wisconsin. The Wisconsin lawyer apparently told her we would have to pay taxes for the total of the California estate to Wisconsin. The California house was sold and funds placed into a trust according to the will. The trust is not in Wisconsin. The two Wisconsin properties are worth less than $400 combined. California was ~$800K (total estate was appraised at, way over estimated, $1.5mill-actual value to us was was ~$800k.)

Her parents only owned property in Wisconsin and lived in California for 38 years and were California residences. I am concerned about the lawyer's motives as well.

I appreciate all advise.What is the name of your state (only U.S. law)?