You can add common code to all the SubPages that will be added to the <head> tag in all published sub-pages. Useful for adding google analytics, chat widgets etc.,
1On your SubPage editor dashboard of any pages, click on the 'settings' from the sidebar.
2 From the settings sidebar, scroll down to find the 'Code Injection' item. In the dropdown menu, select where the code should be injected. Options include all article pages, only the main blog page, header, footer, sidebar, and more. Choose the option that meets your needs and click the 'Save Code' button.