Define tag for posts

I currently have 3 rss-feeds.
1) Press releases
2) General news
3) Both the above

I would like to able to show nr 1 and 2 in the same feed (like nr 3),
but I would like them to be tagged with a certain tag.

So , the news-list should be:
20151021 – Pressrelease – The first newstitle
20151021 – General News – The second newstitle

and so on… So the pressrelease / general news tag is added based on what feed they come from.

Is this possible? I could use the 3rd version just to get them into the same newsfeed, but I guess then I cannot tag them as I would like too.

https://wordpress.org/plugins/feedwordpress/