The HQ account allows you to also create email templates, and share them with your franchisees to allow them to make additional customizations.
The first step is creating a template. Click here to reference documentation for saving an email draft as a template.
Log into the HQ account
Click "Share with Franchisees":
If you add a new location, repeat the steps above, and instead of "share with franchisees" click "unshare with franchisees" and then "share with franchisees" again.
Sharing templates is across all or no accounts, so to share with a net new requires unsharing with everyone to reshare with everyone.