Bismillah ArRahman ArRaheem
The proportionate share of your wife was in trust in the your wife brothers name and her share needs to be given in full.
I.e. if it was to be sold there is a difference in price between now and eight years ago. That difference is likely to be greater in value, and is an appreciation of the value of the share that your wife owns... no one else. So if the property was sold today, that portion should be given to her.
In other words, she owns a percentage of the property as inheritance, not a dollar value.
However, this sentence does not make sense " He gave the shares to all the brothers and sisters according to the value of the property at the time". Who is "he" in this sentence. If the money was given to your wife and she accepted that as her portion she has then sold it and is no longer hers.