Your have multiple options to add emails to your engagement program.
1. You can create all your emails local to your Engagement Program and you can add them to your stream.
2. You can use emails that you already have in different programs.
Did you know you can add emails from different programs to the streams of your Engagement Program?
As you can see in my example above, my Stream 1 includes the 3 new emails that I created locally to my Nurture Example (Nurture Program) but I am also using one email from my Default Program called Testing Lab.
There are different things that you need to consider when you choose the emails that should be included as part of your stream.
I like to have emails local to my program, based on my experience this is better for transparency and easier for reporting. However, there are situations when I would consider bringing into my stream an email from a different program. One of the beauties of the Engagement Program is that Marketo will not send an email listed on the stream more than one time to the same lead. So if by any chance this person has received this email on a different program Marketo will not send this email again.