My favorite news website is 'delfi.lt' which mostly provides excellent RSS feeds. But in addition to them there are also 'RSS Index' feeds which contain some more categories in themselves.
An example of an 'RSS Index' feed for 'Mokslas' category:
http://www.delfi.lt/mokslas/rss/
This XML contains some additional dynamic categories (they are added or removed depending on current events in the world), such as 'Login 2017' or 'Sugalvota Lietuvoje', and links to their separate XMLs. However, calibre seems to treat XMLs of the additional categories as articles and the output in the final ebook is like this:
http://www.delfi.lt/mokslas/rss/feeds/login.xml http://www.delfi.lt/m360/naujausi-straipsniai/login-2017-pasibaigus-kas-labiausiai-istrigo-siais-metais.d?id=74797050&utm_source=rss&utm_medium=rss &utm_campaign=rss http://www.delfi.lt/m360/naujausi-straipsniai/login-2017-pasibaigus-kas-labiausiai-istrigo-siais-metais.d?id=74797050 http://www.delfi.lt/m360/naujausi-straipsniai/login-2017-pasibaigus-kas-labiausiai-istrigo-siais-metais.d?id=74797050&utm_source=rss&utm_medium=rss &utm_campaign=rss&com=1 Wed, 31 May 2017 09:38:49 +0300 http://www.delfi.lt/mokslas/login/papasakojo-apie-snipus-lietuvoje-kaip-jie-verbuoja.d?id=74779490&utm_source=rss&utm_medium=r ss&utm_campaign=rss http://www.delfi.lt/mokslas/login/papasakojo-apie-snipus-lietuvoje-kaip-jie-verbuoja.d?id=74779490 http://www.delfi.lt/mokslas/login/papasakojo-apie-snipus-lietuvoje-kaip-jie-verbuoja.d?
and so on.
How to convert these (sub)categories into proper categories?