So They've Voluntarily Renounced Their Citizenship.

https://news.sky.com/story/sara-sharif-stepmother-of-girl-found-dead-at-woking-home-says-family-willing-to-co-operate-with-uk-authorities-12955847

Now immigration authorities just need to find them.

https://english.news.cn/20230905/84288d3577f043719fe67d2aedfe5884/c.html