According to the Chronicon Lethrense and Saxo Grammaticus' Gesta Danorum (Book 2), Halfdan had two brothers named Ro and Skat who also sought the throne.

According to Ynglinga saga, a Danish king named Fróði the Bold aided Aun's successor Egil against the rebelling thrall Tunni.

Then, one after one, there woke to him, to the chieftain of clansmen, children four: Heorogar, then Hrothgar, then Halga brave; and I heard that ———ela's queen, the Heathoscylfing’s helpmate dear.

It is likely enough that at some time in copying the poem a scribe was unable to make out the exact spelling of these names and so left the text blank at that point to be fixed up later.

According to the Latin epitome of the Skjöldung saga, the sons of Halfdanus are called Roas and Helgo and their sister Sigyna is married to a certain Sevillus.

Friedrich Kluge (1896) accordingly suggested that the line be restored as hyrde ic þ Sigeneow wæs Sæwelan cwen, rendering the Norse names in Old English forms.

But Kluge has been seldom followed by editors or translators, in part because Sævil in Hrólf Kraki's Saga is in no way connected with Sweden so far as is told.

The choice is usually the name Yrs or Yrse, since Scandinavian tradition speaks much of Yrsa the granddaughter of Halfdan and wife of King Adils of Sweden.

Harold leaves two sons behind named Harald and Halfdan, and the story of their vengeance on their uncle Fróði for killing their father Harald is almost identical to that found in Norse texts about Hróar and Helgi's vengeance on their uncle Fróði for killing their father Halfdan.

Name spellings are derived from Oliver Elton's 1905 translation, The First Nine Books of the Danish History of Saxo Grammaticus, via Wikisource.