How can I release my money from a thift saving?

My sister was awarded a settlement in 1990 that was placed in a thrift saving. The thrift savings is telling her that her ex husband has to sign papers to release this money. He has refused all these years, and now he tells her because he is now going through another divorce, he is unable to sign . This is not their money, it was awarded to her. What can she do to get this money released to her? She is a single mother with 3 children at home, and one of those is a special needs child. She desperately needs these funds.