relative clauses without overt modifiers

Consider this noun phrase: Idadi ya waliofariki (from sentence #6799)

the issue is that waliofariki is a relative clause meaning something like "who have died".

The issue is that there seems to be an elided "watu" which serves as the thing that waliofariki modifies. An alternative, is that waliofariki is a noun derived from fariki. E.g. it's those who have died not who have died.

Currently, I am treating these as nouns derived from verbs. (see # 5260)