Have you checked to see what weight the toilet can support? For some reason or another I'm thinking a standard toilet can only hold 400-500Lbs.
Have you beefed up the framing around the toilet? With large people, the wax ring gets compressed and starts to leak in my experience. You might also consider a waxless seal.
I'd just assure her you are putting in the best toilet seat available, no need to tell her what its called or what its designed for. In my mind, she brought up the issue of her size and if you addressing that issue offends her, thats not your problem. She would probably be more upset if you installed a standard everything and ignored the issue.
Have you beefed up the framing around the toilet? With large people, the wax ring gets compressed and starts to leak in my experience. You might also consider a waxless seal.
I'd just assure her you are putting in the best toilet seat available, no need to tell her what its called or what its designed for. In my mind, she brought up the issue of her size and if you addressing that issue offends her, thats not your problem. She would probably be more upset if you installed a standard everything and ignored the issue.