Fingerpicking Melody within a Pattern

Greetings fellow fingerpickers,

The following has troubled me for a long, long time!  I so hope someone will be able to provide an answer that will crack through the walls of my mathematically-challenged skull!  

Basically, as a singer-songwriter, I want to learn how to write instrumental breaks, intros, etc.  I would often want these to fit into the finger-picking pattern used in the song.  Getting a melody to fit gracefully into a picking pattern confuses the living daylights out of me!  I just can't seem to get it.   Any thoughts?