Dynamically Adding Objects

Does Unity support dynamically adding objects to a webplayer build?
Lets say I’ve created my Unity world and I’ve built it and yada yada, so I now have a URL that links to my world.
So if I wanted to delete or add an object from my world would I have to re-build my entire project and re-upload it causing my page to be down for the duration of the re-upload and kicking everyone off, or is it possible to do this on the fly?

Object.Instantiate()

Object.Destroy()

Instantiating Prefabs at runtime

Hope this helped