hmmmmm*ponders* how fine are we talking here?
like powder?
technicaly you can add live sand of a larger volume over the sand you have now. ALthough it will cause, once again, a sand storm, and quite a large one at that seeing how your sand already moves around so easily.
If you realy want to do it i would take out your fish and inverts and corals or such, put them in a subbermaid with adequate water flow and a heater if you decided to go that route.
is this sand made for aquarium use?