I have a few campaigns that my automation consultant advised me to set up a certain way - they actually advised against engagement programs because they aren't as flexible as smart campaigns. FYI - I've been using Marketo for about 18 months now, so still kind of new.
My typical smart campaign setup is this:

Each "Send email" campaign has this smart list and flow:
- Smart List
- Member of X list
- Unsubscribed false
- Flow
- Send
- Wait 2 days
- Request campaign: Send email X)
The Early Exit campaigns are to remove people that accept whatever offer it is that we are promoting. This is the smart list and flow of those:
- Smart List
- Added to list X - if they fill out a form or hit a specific page on our site, they get added to a list
- Flow
- Change campaign status to X
- Remove from list mentioned in first smart list - when they are removed from this list, that is supposed to remove them from the other "Send email X" campaigns. Does that make sense?
If you don't have any wait steps in the Send Email 2/3 trigger campaigns like you have in the Send Email 1 campaign, then you'd need to remove people from the Send Email 1 campaign if they hop off the list. Additionally, to be cautious, I'd also add the Member of List as a filter criteria in the Send Email2 and 3 campaigns, so even though people get requested by the Send Email 1 campaign to flow through the 2/3 campaigns, they don't qualify for them (Send Email2/3 campaigns) if they aren't in the list. Also, instead of setting the send email campaign setup as 1 batch + 2 trigger campaigns, why didn't you set it up as a single campaign with wait steps of 2 days in b/w the 3 send email flow steps?