In Chapter 25, Mrs Jennings invites Elinor & Marianne to accompany her to London. Mrs Jennings seems especially to want company because she had "been always used till this winter to have Charlotte with me" -- I take this to mean that Charlotte was still single the previous year. So Charlotte evidently married Mr Palmer sometime in the Spring.

When Mrs Dashwood is approving the idea, she says, "I have a little plan of alteration for your bedrooms too, which may now be performed without inconvenience to any one." This seems to indicate that Elinor & Marianne have separate bedrooms.