Could it be that Nanxia is unwilling to send the Princess for a diplomatic marriage, so they deliberately claimed she had a serious illness?
Otherwise, the news from the palace wouldn't have spread so widely across the streets, and now that it has spread, a royal decree has even been posted, causing such a commotion that it raises skepticism.
They believe they must see for themselves, or how else can they report back to the Third Prince?
Since the royal decree has been posted, then send someone into the palace to see!
Once they've seen the real person, they should paint a portrait and quickly send it back to the Third Prince. If the Seventeenth Princess is actually fine, then they should paint a portrait of her as a beauty; if she truly is as the royal decree claims, then they should portray the Seventeenth Princess as she looks now and let the Third Prince decide.
