I didn't notice this at first but if you click the pencil icon you can draw a shape to match against instead of searching with text or browsing with the dropdown
Crazy to see this story on the front page of the BBC and now Hacker News too! Ronnie was an awesome guy, and absolutely a part of Rob and Dianne's family, not a "maid" as another comment suggested.
You definitely don't... Unknown contacts show as e.g. "+1234567890 ~Bob" (their WhatsApp display name). When you save them to your contacts it switches to the name you added instead.