Data about administrative subdivisions capital cities

I am looking for data about second or third rank administrative capitals in every African country (the administrative centre of a country territorial subdivision), but I can’t find anything close to what I’m looking for.

So far, I found data on administrative boundaries (GADM, Natural Earth, UN SALB Project, OSM) and about cities (Natural Earth, OSM, Geonames), but nothing that specifically links an administrative subdivision to its administrative capital.

Although Geonames is supposed to provide that kind of information, I briefly checked and found that the data is of very poor quality.