A Hadith whose chain appears connected but contains a narrator mistakenly added is discussed under al-mazīd fī muttaṣil al-asānīd.
• The chain appears connected.
• A narrator’s name has been added by mistake.
• In the example through Ibn al-Mubārak, the addition under discussion is Sufyān.
More names alone are not enough; the addition must be established as mistaken.