The Sun's family.
1) Other stars formed from the primeval molecular cloud that spawned the Sun are probably scattered throughout the Galaxy right now. Even if we had a way to spectroscopically identify them as the article suggests, after 4.6 billion years, there are probably none near enough to detect. Surviving stars as old as the sun, old Main Sequence dwarfs, are quite faint and can't be seen for very long distances.
2) If a supernova did indeed precipitate stellar genesis in the primeval nebula, it's SNR would have probably totally dispersed by now, and any surviving collapsar would probably be either too far away to see, or would be indistinguishable from the many others which litter the galactic disk.