VIs and instrument drivers are NI applications so I'm still not understanding what you mean by 'NI application' but if you choose to use a different instrument driver, then your program has to be written to use that driver. For example, if you are using a LabVIEW plug and play driver and wish to use an IVI driver, your program would have to be changed to use IVI. On the other hand, if you are using an IVI class driver in your program (not an instrument specific IVI driver), then if you switch instruments, install the IVI specific driver for that instrument, and re-configure MAX, then your program does not have to modified. In theory anyway.
If what you mean is if you install a different program that communicates with the same instrument, will your LabVIEW program still work, then yes, as long as you don't run both of them at the same time.
If the above is not what you are asking about, you should add some definitions to your questions. There still seems to be some confusion over the terms 'other method', 'driver',and 'NI application'. Points are not awarded to keeping a question brief. It's much better to provide a very concise question. All of the information in your last post should have been present in your original question.
