A blackmailing Caro plus situation saved by E.?
I thought it was Confounding Caroline by Leenie B. but I'm wrong. Now I tentatively think C. Earle but it's just an idea.
Caro wants Pemberley desperately and knows something about Ramsgate but not much, so invents some suggestive details. She tells her friends or gets Darcy.
So there's a plan, they tell her many details about guys with similar names, for example Wickham, so Williams, Willbourne, Wicky, and for Ramsgate - Margate, Harrowgate. And so on and on. Also some very veird stories. So Caro no longer remembers when, where, who did what. It all happens in Netherfield but the Colonel is there? There was a confrontation where she behaves like a mad person.
The main plan was proposed by E. And there were letters?