Email change to Workflows sent to specific people

We are going through a merger and are moving off one email domain address over to an other email domain address. We have a 100 plus workflows referencing the primary email address.

We reached out to support and were told that there is not an easy way to update the workflows with the new email addresses.

One approach was to add a secondary email address and perform an email merger to allow the secondary to become the primary but, then were told that even with the updated primary the workflow email address would not update.

Looking for ideas / thoughts on how to convert over to the new email domain name without having to touch every single workflow.