As most of us know, Azura is the Queen of Dusk and Dawn, Twilight, Sun and Star, ect. So is She related to Magnus and Lorkhan? If there is a relationship, what is it?

Azura is a daedra.
Magnus was a man.
Lorkhan was apparently a daedra who died, or was slain in the shadows of Nirn's prehistory.

The Tribunal of Morrowind, of which Vivec was part, revolved around tapping the power of the heart of Lorkhan.