[Legal Opinion]
 You can sue for the right of custody, but you can't sue him for not raising children, because his act is trusteeship and not illegal.
 [Legal Basis]
 Article 21 of the Marriage Law stipulates that parents have the obligation to support and educate their children. Children have the obligation to support and assist their parents.
 When parents fail to perform their duty of support, children who are minors or cannot live independently have the right to ask their parents to pay maintenance fees.
 When children fail to perform their duty of support, parents who are unable to work or have difficulties in living have the right to require their children to pay alimony.
 Article 30 stipulates that children shall respect their parents' marriage rights and shall not interfere with their parents' remarriage and married life. Children's obligation to support their parents shall not terminate with the change of their parents' marital relationship.
 Therefore, no matter who has the custody right after divorce, children have the duty to support their parents, and parents have the duty to support their children.