For myself, I don't recall any notable specifics for the time between the capture of Elrond and Elros and the end of the War of Wrath. If so, the implication is perhaps simply that the sons remained with Maedros and Maglor until sometime after the War.
According to a statement from
The Lord of the Rings, Elrond reveals this much at one point:
'It recalled to me the glory of the Elder Days and the hosts of Beleriand, so many great princes and captains were assembled. And yet not so many, not so fair, as when Thangorodrim was broken, and...'
Hmm
Even letter 211 (1958), describing how Elros and Elrond were found, was possibly abandoned, as JRRT ultimately abandoned the detail that
Elrond seemingly meant *Elf of the Cave, for instance. Tolkien might have kept the details found in this letter, but as the meaning of the name arguably reflects the story, it's a bit of a question mark to my mind.
The status of Maglor is a bit questionable too, as Tolkien would (at least twice) imagine that Maglor perished. And as I read the 'evidence' that I'm aware of, the latest version on paper (anyway) concerning Maglor's fate has him casting
himself into the Sea (see the
later Lay of Leithian in
The Lays of Beleriand, where the form of the name is Maelor however).
That all said, Tolkien never got around to any updated
long prose version of
Orthad en-El *Raising of the Star (for this title see Morgoth's Ring, Myths Transformed), and perhaps such a version might have given readers more here.