When I searched fridarey delting lass Google asked me:

Did you mean: Friday deleting lass?

When I recovered from that shock, I found:

A Shetland band called Hom Bru has a song called DA SANG O DA DELTING LASS by M. H. Odie, on their album "No Afore Time" (2003). I think it is probably the same song as the one recorded by Fridarey (or "Friðarey Folk" as they are called at Shetlopedia).

You can hear the entire song (DA SANG O DA DELTING LASS) at Hom Bru's web site.

However, I think the links are mislabeled there; you have to click on the link that says COOPER'S REELS in order to hear DA SANG O DA DELTING LASS.

It's a beautiful song, but it's sung in the Shetland dialect, which I find even harder to understand than Scots.

What I can understand of the story is this: There is a lass who "comes up da brae singin" because "Da lime(?)-boats o Deltin are sailin awa." Later she is "feart" when "The high hills o Deltin are covered wi snaw." Still later she comes "doon da brae greetin [crying]." "Nae mair she is singin for da mornin is bringin ... ill news tae Deltin."

I'm not sure what the "ill news" is, but Wikipedia tells of "the infamous 'Delting Disaster' of 21 December 1900 when twenty-two local fishermen where lost during a storm, decimating the community [of the village of Firth, in the parish of Delting]."

In another forum, I read that the words and music to DA SANG O DA DELTING LASS is in this book:

Songs and Sights of Shetland by Christine M. Guy ([Lerwick]: Shetland Arts Trust, 1995).