Editable Exclusion List during Active Program

I occasionally build out email campaigns using Programs and leverage the Exclusion list option to opt out contacts. The challenge I face is when the opt-out list is dynamic and I don't have the ability to edit the exclusion list. 

Example use case: 

I am sending out a multi-stage email drip to invite customers to a webinar.

1. Email 1 goes to contacts
2. Email 2 goes to contacts that have not registered

Some of these webinars are one off type so we don't have the registration data available in a place that Gainsight can access. This means I'm using a csv export to exclude registered contacts before email #2 goes out. 

Challenge:
Once a program is active, I can't make changes to the participant config. This means I can't remove contacts in between email 1 and 2 without removing them from the participant list one by one.

This has left me with needing to create two separate outreaches which somewhat defeats the purpose of the Program functionality.

Ideal state:

The exclusion list is always editable so I can update the list with new emails in between email 1 and 2. 

Another idea, provide an option to change the participant state in mass. That way I could upload a csv for the additional contacts I'd like to remove.