Here are some thoughts about my experience. I didn't know what I was doing,
I helped my father through his chemo. I discovered that for food it is important to go with the flow. What tastes good one day may seem nasty the next day. For my father, I tried to plan good nutrition and at first I wrongly pushed my plan on him. He lost a lot of weight and I realized calories in any form were "good" nutrition. I kept a variety of things on hand to prepare small meals and never pushed him to eat anything. We found flavors of Ensure that were palatable and always kept them on hand. The meat and potatoes guy developed a liking for flavored yogurt cups and fruit salads too. We began to look at it as an adventure in discovering what was palatable. On his better days we would go to the store and wander the aisles looking for possibilities.
We made sure his papers (a Will and a letter regarding his cremation and disposition of his ashes) and power of attorney (limited to one person) were in order and then we talked no more of the details. Time was too short to waste on that. Decisions about his material possessions were deferred. My siblings and I assured him not to worry about any of it, that we would take care of it all per his wishes.
I found that there were just too many variables to make a solid plan. I wanted to have everything in place, but it was not possible. My father lived much, much longer than they predicted. In hindsight I see that we became equal partners in this and I certainly wasn't in charge.
I find it difficult to think of and write of those times. It was tough, but we did OK.