Save Vanra quest (spoilers)

[Theinvoker]

If you are here is because you already did it, otherwise go out.

In my first playthrough i didn't meet Lora at the barracks. i got the quest from Mayrina just exploring the city, so i knew Vanra was inside Ethel. I didn't get the item...ok
But even if i talk to Lora first, how could i know i don't have to kill Ethel? after talking to her, it's logic to go directly to The Blushing Mermaid and i can never know Vanra has been eaten by Ethel or that i have to destroy mushrooms first.

So is there something that point me to Mayrina after getting this quest from Lora?

[YumboYack]

https://www.gamespot.com/articles/baldurs-gate-3-save-vanra-legendary-guide/1100-6516833/

[Theinvoker]

ok if i talk to grisly i can (not always) find out that that Grisly is Ethel and she confess she has eaten Vanra BUT there is nothing that directs us to Miryna

I'm already in the right place, why should i go exploring the city searching for something i don't even know exists