Insert Grocery Crud into another crud in codeigniter - codeigniter

Question

i want to insert grocery crud in to another crud table.can i do it? i have tried it but it shows two error called
"Undefined property: Boq_doc_controller::$project_list_model" and
"Fatal error: Call to a member function show_boq_id() on null in
C:\xampp\htdocs\rcj-constructions\back-end\application\controllers\boq_doc_controller.php on line 42".
simply there is top level crud and there is a view boq button instead of edit or delete button.once click the view boq button it should go to the grocery crud.i will add my code. any one can plz help me.
thank you.
my top level crud model
class Project_list_model extends CI_Model {
public function get_all_project(){
$this->db->select("project.project_name, project.id, client.firstname, client.lastname,staff.firstname, staff.lastname, project.location,project.category, project.start_date, project.end_date");
$this->db->from('project');
$this->db->join('client', 'project.client_id = client.client_id');
$this->db->join('staff', 'staff.id = project.staff_id');
$query = $this->db->get();
return $query->result();
}
}
my top level crud controller
public function index()
{
$data['project_list'] = $this->project_list_model->get_all_project();
$this->load->view('project_list_view', $data);
}
my top level crud view
<?php foreach ($project_list as $project){ ?>
<tr>
<td><?php echo $project->project_name; ?></td>
<td><?php echo $project->location; ?></td>
<td width="40" align="left" ><a href="<?php echo base_url();?>index.php/project_list/index" >view BOQ</a></td>
</tr>
<?php }?>
my grocery crud controller
function __construct()
{
parent::__construct();
//load the Grocery_CRUD library
$this->load->library('grocery_CRUD');
$this->load->model('Project_list_model');
}
public function boq_doc(){
$crud = new grocery_CRUD();
// set datatable theme
$crud->set_theme('datatables');
//set the table name
$crud->set_table('staff');
$crud->columns('item_no','description');
$id = $this->uri->segment(3);
$data['single_boq'] = $this->project_list_model->show_boq_id($id);
//view output
$output = $crud->render();
$this->_example_output($output);
}
// edit /view /delete plan
public function boq_doc1()
{
// load plan
$this->grocery_crud->set_table('boq');
$output = $this->grocery_crud->render();
$this->_example_output($output);
}
// _example_output
function _example_output($output = null)
{
//load edit /view /delete plan
$this->load->view('our_template.php',$output);
}
// /._example_output
}