My Mom is 94, bed bound past 5 yrs, & had 4 TIA's.

Sounds like she is doing pretty well in the eating department. I'd try serving things that she can and will want to eat for dinner. Cottage cheese in a pretty bowl with a slice of peace that she eats is better than a hamburger that she spits out. By the end of the day it may be she is just tired and weaker and swallowing is just more difficult. Have you considered "milk shakes"?

When my husband was in a tcu, one woman "ate" a complete meal by chewing it and spitting each mouthful into a glass. While this is pretty disgusting for others to watch, it is apparently not unheard of. Give Mom a sturdy disposable cup or glass to spit into if she must. Don't make her feel bad about doing it. But work on finding things she might be able to eat more easily in the evening, and reduce the portion sizes so the meal doesn't seem overwhelming.

At 94, Mom's experiences should focus on Joy and not on "good" behavior. Unless she is losing weight, I wouldn't worry about her not eating a traditional third meal for the day.

mountaingirl7, when someone is bedbound, they are burning less calories than someone who is mobile. Thus the reason for eating smaller meals.

Jeannegibbs, above, had a great idea about milk shakes.... even Carnation Instant Breakfast stirred into milk is good [depending of the sugar content].

Oh, I found some info on the chewing and spitting out from other posters. https://www.agingcare.com/questions/part-of-dementia-to-eat-and-spit-out-food-156999.htm