'Call of the Mother' Milestone?

I recently came back to playing The Sims 4 after a hiatus (since Feb 2023), and I thought I'd do a 'Heroine Saga' as my first new save file.
(Don't know the official term for the challenge, but it's when you play a Sim from birth until death, and try to achieve ALL the things with one person.)

Unfortunately, I had no idea what I was getting myself into when I decided to include Milestones into the saga, because half of them seem buggy lol.

And while most of them are discernible from their title, some of them are a bit more obscure. Not to mention, I can't find a master guide on them.

So please tell me: What is this 'Experienced the Call of the Mother' milestone, and how do I go about achieving it? I can't find answers anywhere!