Translate a website into different language, but use different default language
We have a website that has a norwegian (NO) language as default. We support few languages on the website as well. One of them is british english (EN-GB). Now we would like to add american english (EN). The problem is, when I add american english language (EN), the whole page is in norwegian (NO) by default. Obvious scenario here is that we would like to reuse the british english page instead of copy-pasting everything. Is it possible to add a new language, but base on different default language (another that we currently support)?
I am not able to change default language in 'SITE LANGUAGE' section in 'SEO & SETTINGS' - this option is disabled (I do not know why).