Most Beloved Sister (Allrakäraste Syster) is a 1949 fairytale by the Swedish author Astrid Lindgren. It was originally included in the collection Nils Karlsson-Pyssling : sagor (OCLC185229564), then re-released in 1973 with illustrations by Hans Arnold.
Daddy likes mommy the most and mommy likes the new baby the most, but seven-year-old Barbro's secret twin sister Ylva-li only likes Barbro whom she calls Most Beloved Sister. Ylva-li is the queen of the golden hall. You reach it by crawling down the hole under the rose bush, Salikon. In the hall they play with their dogs Ruff and Duff, feed their little white rabbits and ride their horses Goldenfoot and Silverfoot. They ride through the Big Horrible Woods where The Evil Ones live, to The Good Ones who offer cookies and sweets from the big stove in the middle of the meadow. They ride on to The Most Beautiful Valley in the World, where the flowers sing and the trees play music. When standing on the bridge over the little brook, everything turns silent and Ylva-li tells her Most Beloved Sister a horrible thing.