I have a track featuring a lyric from a previous Challenge, but which I revised several days ago, and which now has music composed this week by a FAWM/50-90 member. So I know it's OK to post that.
However, the vocalist and the bass player aren't members.
Do you folks think it's still in the spirit of the Challenge even if not all collaborators are members?
Thought I'd try to get a consensus before I post the song. 
Yes, certainly!
Yep - I’ve had assists from folks who aren’t FAWMers and they have no problem with me posting.
Good way to get them to join
I often post collabs that are not with members. I do ask them first though
Thanks so much, folks.
I'll go ahead then.
(No problem regarding the non-members. I was simply concerned that posting a song that included non-members might be considered against the spirit of the Challenge.
)
I'm still pretty new around here -- this is my first 50/90 -- but I've gathered from several old-timers that 'cheating' here is only considered cheating yourself. The goal of writing 50 songs isn't a competition; it's a motivation for YOU, and the benefit that comes from it is also for you. I posted my song LUCKY in spite of it being years old and a collaboration with another musician who isn't here; in the spirit of being honest about it, I mentioned all that in the song's post, and said that I wasn't going to count it as part of my 50. Nobody minds.
Crazy thing is that in my 12 years doing FAWM and 50-90, I'd never paid attention to whether members were assisted by non-members in their music. So I wasn't sure what the deal was in that regard. Now I know.