Miscellany

public class Parent {
     
    private Set<Child> children = new HashSet<Child>();
     
    ....
     
    public boolean removeChild(Child child) {
        return children.remove(child);
    }
      
    ....
}

....

Parent parent = // load parent with children
Child childToDelete = // find child to remove
parent.removeChild(childToDelete);
// commit transaction