Herb,

You might enjoy the Berklee Songwriting course that's free on-line. I really enjoyed the class, and I will take it again when it becomes available. I have it watchlisted. I don't get spam from Coursera. There are several folks here who have taken this and other classes and I think they would vouch that they aren't being spammed either.

Here's the link to the course:
https://www.coursera.org/instructor/~326

As I read your post, I think of the instructor's tool called 'the boxes'.

He talks about each phase of the song, can be thought of 3 main boxes, with the first idea or box being able to fit into the idea or 2nd box, all of which can get packed into the 3rd box.

If you find that a middle 'box' or the ending 'box' can't contain the others, or perhaps the middle box is the biggest idea; then swap them around, trim, etc.

There are exceptions of course. While I love Jimi Hendrix' "Little Wing", I couldn't explain what it means in any logical way - which I think was the point.

But if you have a story to tell and you are using melody and chords to plant it in someone's brain, then it should have some logical sense to it.

Anyways, if you're interested, sign up for a Coursera account and watchlist the course.