The Little Country Doctor

The female protagonist transmigrates into the body of a village girl who has lost both her parents and has a younger brother. Her house is sold by her uncle. Her 13-year-old fiancé, who is also a few years younger than her and has lost both his parents, comes with his three younger siblings and asks her to move in with him. The female protagonist takes her brother to live with her fiancé.

Can the relationships between the characters be a little more stable? One minute they're uncle and aunt, the next they're brother and sister-in-law, and then back to uncle and aunt again. They really can switch roles so easily!