] How did Mrs Jennings "meet" them in Exeter and "discover" them to be relations of hers? I'm puzzled how this exactly happened. Then she invites them over although neither Sir John nor Lady Middleton have ever seen them before. What did the sisters do in Exeter and how could they call that off immediately?

It just seems so convenient that they meet her in Exeter, they are related and they can just trot off to visit. Could they have just been waiting in Exeter to latch onto someone who could put them into a position to advance themselves? Would any distant relation do? And was everyone in their class related to everyone else either directly or through marriage? I can see them going to Exeter just waiting for someone like Mrs. Jennings to come along and take them home. I ever thought of this before, but it makes them a bit more devious in my eyes.