Interesting topic, Ladies. Thinking about the two sisters composing the letter together leads me to wonder why Caroline alone is supposed to write in the first place. If both sisters are supposed to be Jane's friends--as they declare themselves to be when she's convalescing at Netherfield--wouldn't it be taken amiss if Mrs. Hurst didn't send regards before leaving the country? Am I missing some crucial bit of etiquette here?

Incidentally, I agree about Louisa helping to compose the letter. Looking back to the first letter Jane received from Caroline (on that infamous rainy day) it has an air of being from both sisters, IMO. ("If you are not kind enough to dine with Louisa and me...") Not only would Caroline want to seek her sister's help with such a vital communication, I imagine it would be such a good opportunity for them to be catty together. ;-)