Edit an active automated email series

I plan on having several communications -- but I have not drafted every email yet.  So I'd like to be able to append to the end of the campaign.  

Is the only way to add new emails to a campaign to copy the series and start over?      That seems to prevent anyone already in the current series from receiving my newly added emails.   I can see this getting really messy if I can't figure out an alternative.

I'm sure I cannot be the only one who needs multiple emails but don't have the all ready to go right away

Am I missing something?