I found a solution: I don't serialize the parents, and I use this function after deserialization in the "Controle" class:

    [ProtoAfterDeserialization]
    protected void OnDeserialized()
    {
        if (ControlesInternes.Count > 0)
        {
            foreach (var ctl in ControlesInternes)
            {
                ctl.Parent = this;
            }
        }
    }