You might enjoy listening to this when you have 10 minutes:
"The Last Batch of Fudge" – by Michael Imber
https://themoth.org/stories/the-last-batch-of-fudge
The Moth's web site is really slow so here's another link to that story in the episode:
Do tell -- what's it called? Sounds like a great read.
I was thinking of biscuit recipes where mixing was often done by feel of the dough, rather than exact amounts. Grandmas could just "feel" the amounts needed for their biscuits.
I do see recipes for it online but they look very different (spices? cream?).
That card was has several fun comments and lots of history to my siblings who added to the crustiness of this card.
The original card I remember said to use lard or you can use margarine if you "haven't slaughtered a hog recently".
The recipe in mealie was modernized and tested more.
If she's like my mother, she probably thinks of these recipes as a connection to her parents and grandparents. The importance is not in the finished dish, but in the history of this specific artifact, including: the hand writing, the original index cards, the references to the bowls she remembers as a little girl. I understand this. When I see my grandmother's recipes, hand-written in broken English, it makes me smile, because I can't not read it in my grandmother's voice. Ok, these aren't cakes and cookies, so there's no need to be precise, so I do the recipe updates in my head anyway.
When updating the recipe, consider this. If you're laying it out on paper, at least keep a reference to the original recipe, a photo, etc. I have a professional cookbook like this. It has excerpts from journals from the 18th or 19th century with the original recipe, and also recontexualizes them for today's ingredients, tools and techniques. You get both the history and the dish.