there are several ways to treat this "next" next action and all actions coming after that, that you might want to record all ready because you thought of them and you don't want to lose the idea (or because there is a commitment):
- you might define "e-mail summary to boss" as a project and "review notes" would be the first action for that project
- you might define your next action as "review notes (for e-mailing boss)"
- you might define a waiting for: "WF: review notes (to mail boss)
- you might start reviewing the notes and in that same flow send the mail to your boss, and not need to record that next action at all
- you might store thos next next actions in project support material (and store it as "rough planning for the project")
- ...

Just try something (maybe one of these or something completely different): give it a chance, see if it works for you. If it does: do it again. If it doesn't: try something different until you find some approach that works for you...

greetings,
Myriam