The healthy partner, if there is one, could be too busy working to complete all the household chores so non-medical help could be required, too. Because no one knows exactly what the future will hold it's hard to decide whether you need additional disability insurance and, if so, how much is appropriate. The best you can do is to think of some things that could happen and think about how you'd react to them. Take a look at your finances and estimate what would happen if an adult had a stroke and it was necessary to move them into a nursing home. Include both income and expenses.
Estimates are fine.
You don't need to be overly accurate. The goal here is to just get a feel for how tough it would cost and how much income would be needed to keep things going. Prepare a basic budget with the revised income and expense figures. You'll probably want to also do a scenario that's not quite so drastic, perhaps where someone is disabled for a year or two. Under this circumstance you'd expect that the disability income required would be significantly less.