What do the route variations establish?
1. A known teacher–student relationship does not exclude a further link in a particular report.
2. An added link does not by itself invalidate the other route: both hearings may be genuine, or one version may reflect an omission/insertion requiring examination.
3. Explicit hearing, narrator precision, other pupils’ transmissions and supporting circumstances guide adjudication.
Muslim’s examples support an argument about the coherence of a general criterion; the status of individual routes needs its own source criticism.