I deal with nauseaa because of my meds - rice congee is a comfort food and when made with a faair amount of ginger and garlic works for me.
I take a whole chicken, cut into quarters. Cover with water, put in one onion cut into quarters, a golf ball sized piece of ginger peeled and cut into discs. Bring to a boil and turn off. Let sit covered until the water is cold. Remove all solids from the broth, take the meat off the chicken and reserve. Toss the dead aromatics, chicken bones and skin. Put the broth in the refrigerator and chill. When the fat solidifies, remove.
Measure the broth. Take 2/3 the rice that would normally make with that amount of liquid, wash thoroughly and put into the broth, and simmer with another golf ball sized piece of ginger, an onion chopped and the chicken meat [however much you feel like putting in, since they are trying to build up, put it all in. ] and cook until it the rice is almost dissolving. THink of it as a rice variant of blancmange. [of course you can make it with leftover chicken and premade broth also]
I also nibble the candied ginger pieces.
Fat makes nausea worse, and sometimes the type of meat you are trying to eat can trigger nausea [right now anything pig in nature makes me vomit. no bacon, no bangers, not even a nice chop=( ] I have been able to manage some days with the thoroughly american peanut butter and jam sandwiches made with toast, so how about toast with the 'mite of your choice? How about fresh fruit as available - small nibbles of melon that is ice cold goes down a treat especially if it is very juicy. Ice cold grapes are also good, and I went through an orange phase and a pomegranite phase when they were in season.
Thinking about it, I would try making up a plate of very cold suculent fruits - small slices of melon, perhaps strawberries, grapes, orange pieces, banana. Add toast, table water biscuits, export crackers, arrowroot digestives. Maybe add some almonds, the honey and sesame seed boiled candies from middle eastern stores, and bits of candied ginger.
That way they can sort of nibble a tiny bit at a time over a long time instead of having to sit down and be expected to do a meal. it is amazing how much one can nibble over a long time if it is set down as a nibble plate by their chair or bed. Make sure they have lots of ice cold water, one of the problems with nausea is getting dehydrated as well.