Barbara,
Perhaps what Peter is talking about is that he feels there should be more of Sara's life told in the song. Maybe relating some of her joyous moments along with some almost forgotten aspirations of Lisa's could be used to contrast the overall bleakness amd hopelesness of the situation. Take a look a Gillian Welch's lyrics, particularly "Annabelle". If you don't have them, let me know and I'll post them. Personally, I don't find anything wrong with the direct approach. What works for some songwriters doesn't work for others. If it feels true to you as a writer and performer, that will come through.
Dave T