Depends on what the deed says and what the man's estate plan is (will or no will).
If the house is joint tenants with right of survivorship, and the married man dies, the house automatically goes to the surviving brother. If the house is tenants in common, the man's estate would control where his "half" of the house goes. If the deceased husband has a will that gives the house to his wife the wife would own half and the brother half. If the deceased husband died without a will and the house is tenants in common it is possible the wife and deceased husbands children will split ownership of the half and the other half will remain owned by the brother.
You need to have an attorney review the deed and also see what the man's estate plan is.
This is not legal advice nor intended to create an attorney-client relationship. The information provided here is informational in nature only. This attorney may not be licensed in the jurisdiction which you have a question about so the answer could be only general in nature. Visit Steve Zelinger's website: http://www.stevenzelinger.com/
A serious controversy between wife and brother in law WILL happen.Ive seen it many times.Resolve ths issues now before it is to late and cost prohibitive.
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I agree with the first two responses, but want to ask the chronology because I am curious. Was the property deeded to man and brother BEFORE man was married or AFTER he was married? If before, how much later was the marriage?
I may be guessing or not licensed in your state. No atty/client relationship exists.