Hmm.. By diagraming sentences you mean those drawn like a tree structure from left to right?

I'm just thinking that if, based on the fact that those mentioned adverbials behave more like complements than modifiers and thus are necessary to the pattern, I expand the basic five to basic seven (S+V+A and S+V+O+A) and would help the students distinguish this subtle difference. Otherwise I'd have to create subcategories for these adverbials under S+V and S+V+O+A as you said... which I'd think students would accept better than just listing them as mere exceptions. :o

EFL students can give you a hard time!!! But.. they are a vital income source!!