Classes with operations extending another class

I have a class called cliente

class cliente {
    private $id;
    private $nome;

    function getId() {
        return $this->id;
    }

    function getNome() {
        return $this->nome;
    }
    function setId($id) {        
        $this->id = $id;       

    }

    function setNome($nome) {        
        $this->nome = $nome;
    }
}

And two other classes called selecionaCliente and insereCliente these two extend the cliente class:

<?php
require_once 'cliente.php';
class insereCliente extends cliente{
    private $pdo;           
    function __construct() {
    require_once 'conbdd.php';        
    $db = new conbdd;
    $this->pdo = $db->conectar();        
    }
    function selId(){
        try{
            $sel=$this->pdo->prepare("SELECT name FROM clientes WHERE 
            id=:id");
            $sel->bindValue(":id", $this->getId());
            $sel->execute();
            $temp=$sel->fetch();
            $this->setNome($temp['nome']);
            return TRUE;        
        } catch (PDOException $ex){
            echo $ex->getMessage();
            return FALSE;

        }        
} 
<?php
require_once 'cliente.php';
class selecionaCliente extends cliente{
    private $pdo;           
    function __construct() {
    require_once 'conbdd.php';        
    $db = new conbdd;
    $this->pdo = $db->conectar();        
    }
    function insNome(){
    try {
        $ins= $this->pdo->prepare("UPDATE clientes SET nome=:nome WHERE 
        id=:id");
        $ins->bindValue(":id", $this->getId());
        $ins->bindValue(":nome", $this->getNome());
        $ins->execute();
        return TRUE;            
    } catch (PDOException $ex) {
        echo $ex->getMessage();
        return FALSE;
    }        
  }        
}     

I want to validate and store client data within the cliente class through the class that will use the information

If I instantiate the two classes selecionaCliente and insereCliente and set an information in selecionaCliente will I be able to retrieve this information through the instance of class insereCliente , or does each instance create a different client? If so, how could I make all classes use the same instance of cliente ?