Church members have expressed concern lately about my dad’s cognitive ability to care for himself.

Rob,
Strongly recommend you and your sister have a Family Meeting ASAP to work out a Caring Plan. A good guide for this is the book "Caring for your Parents" by Hugh Delehanty and Elinor Ginzler. You both have a lot more to consider than who dad should stay with during his final days. And don't be surprised if he rejects every solution you finally present to him. You are entering the stage of family life known as "role reversal" This simply means it is now your turn to step up to the plate and take care of dad despite himself. Like a child, he may stubbornly resist actions any responsible adult would take; try telling him it is time to turn in his car keys and see what happens. Yet you know he poses a danger to himself and to others on the road. So you have to do what is right even tough it seems wrong to buck your own father.

He probably is, at 82, "losing it", so you MUST act to protect him or YOU become part of the problem. Convince him to get a "Geriatric Assessment" (look it up). It's covered by Medicare and will allow an experienced geriatrician to advise you and Dad. The Alzheimer's Assn. will recommend a place near you where this 2 hr. visit can take place.

Have you talked with your dad's doctor and shared your concerns? Perhaps a written list of observations will alert him/her, as well, and lead to testing, etc. A neurologist can be helpful, as well. Best wishes.

There are solutions and moving in with you is not the only one. Now that you are out of denial, you can start talking with people and exploring options. If you live close enough, you might consider a daily visit to help organize his day.