I think the very small portion is a good idea if you want to "plate up" . You could invite her to look at what you're doing in the kitchen and say "is this enough - you can always have seconds"?
I do this for my mother-in-law who eats like a bird.
Yesterday she had a tiny portion and I gave her another tiny portion to take home for lunch/dinner today.
She likes not eating alone but no longer manages proper sized meals.
It's kind of you to be so considerate of her - in spite of everything.
What decade were your grandparents born?


