Destruct order/What is reference counted?

Are resources refence counted, or variables? I have a muscat_module method I wrote which is of the form: $new_resource=make_new_object($old_resource); each resource is a C++ object, and I have to stop $old_resource being disposed of until $new_resource has also been disposed of. This is a strict condition, even at end-of-php-page-mass-destruction time. It seems like there is no destroy order at end-of-page time? Whats the best way to enforce it? I think I am going to have to wrap all the C++ objects in more C++ to implement reference counting- aggh. Surely there is another way? Sam