In the Silmarillion Maglor is (allegedly) the sole survivor of his family.
Here, it's someone else.

And death shall have no dominion.

The final installment of The Price of Eternity series.

After the destruction of the old universe, Vanimórë, sitting outside ‘Time’ in the ‘Monument’, believes himself a failure for creating new universes that are too much like the old. His mind is a desert, the hurt of Eru’s revelation driving him into isolation. 

Eventually, he decides to look into one of these universes, where the Valar’s hand lies heavy on the Elves and in particular a youth growing toward maturity.

A story of Fëanor, and Fingolfin, the secrets woven into Valinor, the cold calculation and lies of the Valar, the forbidden passion that nevertheless grew between the half-brothers, and their determination to break the chains that were wrapped about them — with a little help from an unknown ally. 

They were Fireflower and Starfire, their lives linked over countless universes, drawn together by a bond that neither death nor Power could break.

Chronologically takes place after Magnificat of the Damned Book IV and is part of that ‘verse. (And other ‘verses)

Strength isn’t just about how much you can handle before you break.
It’s also about how much you must handle after you've broken.

In which Maglor is creepy and insane. His family tries not to care.

The last Elves of Middle Earth sail to Valinor. With them is one of the few people Fëanor claimed to be his friend.

The House of Fëanor has no choice, the Oath will be fulfilled.

Glorfindel is dead; only he isn't. As he wakes in Angband starring into the eyes of his husband, he finds himself enlisted into the most dubious group of kinslayers, traitors and dark elves to save dragons, steal Silmarils and topple Morgoth from his throne... well, at least, that used to be the plan.

Nerdanel considers her children, and why Curufin was always special to Fëanor’s heart.