Looking for a way to use Snippets on templates that can not be removed

I've got default snippets added to my email template, but I want to make sure that no one can remove or replace those snippets when they are creating the emails. Has anyone found a way to add a snippet that can not be edited with the email editor? Our use case is for global footers that need to be used across multiple footers, we don't want to be able to manage the content in a single place but also ensure that it always appears and can't accidentally be removed from the email. We used to just use formula fields to do this, but that is no longer supported on large email sends.