If your sister never, never, ever, uses the stove, she would be ok with taking out the fuses or turning off all power/gas to the device? That's the only way I could ever see this happening - or just removing it and replacing it with cupboards.
I bought element covers for my stove at one point - quite sure that I would never turn on the elements accidentally. Guess what - it happened. Luckily I was right there and turned off the burner in time - the cover was burnt but no other damage. There are just soooooo many things that could go wrong.