Can Templates include sub-Templates? For example, consistent signature/unsubscribe footers

[e-Dan-K]

On my site pages, I have an {% include 'project/includes/footer.html' %} for appearances of pages throughout the site. I feel there should be something similar in emails, for signature and unsubscribe links. Is there a similar {% include %} that can reference post_office templates? If not, can there be?

[selwin]

Hi there, this is something that I definitely want to have. Any suggestions on how to implement this?

If someone is willing to put in the work to figure out how this may work, I'd be happy to accept a PR for this.