What are the chances of a stepmother getting custody?

My 31 yr old brother recently ped away. He had full custody of his two children from his first marriage and six days after he died the "real" mom came and took them from their step mom who had lovingly raised them for 7 yrs. They didn't want to go, but she made them. Their ages are 12 & 10. This sorry excuse for a mom never paid the court ordered child support since loosing custody to my brother, nor did she provide health ins. or any other form of support. My brother and his wife were soley and gladly responsible for these children. My brother also had another 1 1/2 yr old daughter with this wonderful lady and she has a son of her own that my brother loved, as his, as well. Needless to say, this has torn the family's already broken hearts into pieces. And my brothers wife feels like she has lost her husband AND 2 of her children. She has filed with the court to get them back or at least get visitation rights. What are her chances? Also these kids say they are unhappy and want to come home.