In Chapter 19 we meet the Palmers, Mrs Jennings's "other son and daughter," who were actually Mrs Jennings's younger daughter Charlotte and Charlotte's husband. Charlotte is described as:
several years younger than Lady Middleton, and totally unlike her in every respect. She was short and plump, had a very pretty face, and the finest expression of good humour in it that could possibly be. Her manners were by no means so elegant as her sister's, but they were much more prepossessing. She came in with a smile -- smiled all the time of her visit, except when she laughed, and smiled when she went away
Charlotte seems to be more like her mother, though maybe not as observant or quick. Lady Middleton is definitely not like either her sister or her mother! Another pair of sisters who seem to be unrelated to each other -- how was it that Lady Middleton managed to become the well-bred (though boring) woman she is?
Mr Palmer is a bit of a cipher at this point, being "grave looking young man of five or six and twenty, with an air of more fashion and sense than his wife, but of less willingness to please or be pleased." But his wife seems to think that everything he says or does is quite humourous, so she is not unhappy in her marriage -- his feelings on the matter are less obvious, but seem to tend in the negative direction. :-)