From Longman Dictionary of Contemporary Englishsister paper/publication/company etcsister paper/publication/company etcCONNECTED WITHa newspaper etc that belongs to the same group or organization the Daily Post’s sister paper, the Liverpool Echo → sister
Examples from the Corpus
sister paper/publication/company etc• At any rate, the most prominent critic was Nick Seitz, the editorial director of Golf Digest and its sister publications.• And our sister paper the Sunday Mirror revealed yesterday she had given 37-year-old Bryan a room there.• Journalists on our sister paper, the Liverpool Echo, also won awards yesterday.• Our sister company, the Snakes, made the first assault in the morning and received very little opposition. 