After I Transmigrated, I Became a Medicine Immortal

When her grandfather, whom she hadn't seen in ten years, is kidnapped, the heroine, Mu Lin'er, agrees to help her captor, Liu, retrieve the Longevity Stone mentioned by the ancestor of his family. After transmigrating to another world, she becomes another Mu Lin'er, with the same name. She also gains an older brother, and the two siblings are both considered useless. Their family abandons them in a remote village...