Noindex RSS Feeds or Forum Categories?

[Sovereign Grace Singles]

Hi,

I was attempting to noindex in robots.txt certain categories or forums on my site. However, I noticed that the urls do not follow a consistent pattern. For example:

https://www.christforums.org/forum/34-conservative-news/

This is the main Conservative News category. However, threads created in this category look like this:

https://www.christforums.org/topic/11829-man-who-led-protests-against-cleveland039s-chief-wahoo-jailed-on-charges-he-stole-money-from-native-americans/

Notice how the url doesn't contain /34-conservative-news/

Therefore, I do not see how to noindex this category and all threads contained in it. I can't noindex /topic/ because other forums contain threads with the same pattern which I want to be indexed.

Another option which doesn't exists would be to noindex a specific account which the RSS is syndicating as or noindex each RSS feed.

Any help on how to achieve this?

Thanks in advance,

CF