Western Frisian should have fallback to Dutch

Western Frisian is a language spoken in the North of the Netherlands, in the province of Friesland. It has about one million inhabitants, and Ubuntu is not fully translated to it. However, there are translations present in the Ubuntu repositories.
When someone chooses to use the translations she or he will see a lot of English strings.

There should be a fallback string added to /usr/share/language-selector/data/languagelist that sets Dutch as the fall back language, most preferable the whole Dutch line pasted after the Frisian section since Dutch is the second mother tongue of most Frisians and they live in society where Dutch is the main language, apart from the province -- which uses both languages -- and a few municipalities.

A Frisian operating system would be a huge selling point in a province where the Frisian language is very important to quite a few.