Adding song to playlist doesn't add to library?

I've been using GPMAA for a while now, and recently started checking out a lot of new music via radios and stuff.

When I hear something I like, I'll add it to a playlist (say Hip-Hop), but then I'd also like it in my library, so I add it to Library.

This gets a bit tedious when checking out new music, adding a song I enjoy to both. What do you guys do? Just add it to one or the other?

Seems like adding to a playlist should auto-add to your library, but maybe I'm taking crazy pills.

(Using GPMAA on Android/browser)