keypaths working across to-many relationships

NSPredicate *predicate = [NSPredicate predicateWithFormat:
    @"ANY %K like 'Matthew'", relationship(department.employees, employee.firstName)];

NSPredicate *predicate = [NSPredicate predicateWithFormat:
    @"ANY %K like 'Matthew'", relationship(Department.new, employees, Employee.new, firstName)];

If you could convert to c so it works with @to-many or something that would be cool. :)
My c is non existent.