How does the application work at a high level, what rights does the family member receive, how long does the status last, and how can it become independent or longer-term where officially stated?
Applicants obtain the documentation, apply online (embassy), submit the visa requirements and pay the visa fees. The visa is valid 90 days from issuance and extension is not applicable; the stay is 2 years with multiple entry (residence permit), the holder may reside in Nigeria as a dependant of the accredited diplomat, and family or group applications are not available. The official source does not state whether or how the status can become independent or longer-term.
See recorded sources
Limits of the record- The page does not state whether or how the family member's status can become independent or longer-term.