«وَيُسْتَدَلُّ عَلَى مَعْرِفَةِ اسْمِ الْمُبْهَمِ بِوُرُودِهِ مِنْ طَرِيقٍ أُخْرَى مُسَمًّى»
The identity of an unnamed narrator is established through another route in which that narrator is named.
Suppose one chain says “from a man, from Khālid,” while a securely matched route of the same report names “Saʿīd, from Khālid.” If the surrounding chains, chronology, and wording support that identification, the originally unnamed person may be identified.
A resemblance between two chains is not enough. It must be shown that the second route actually specifies the intermediary in the first, rather than transmitting a distinct report with a similar text.