You know more about such things than I do, but I thought that for some time there was a parallel Novus Ordo Campos diocese and a traditional Campos diocese. If this is not the case, then I misremembered. The way I remembered it, was that after a while the Novus Ordo tried to take control of the Diocese and appointed a new Novus Ordo Bishop, and then Mayer set up his own Churches and carried on with tradition with his faithful, and then the SSPX Bishops consecrated his successor in Campos.
Bishop Castro de Mayer retained integral tradition in Campos until he retired in 1981.
He was then succeeded by the modernist Bishop Navarro.
At no point did Bishop Castro de Mayer ever contest Bishop Navarro’s jurisdiction, or declare that he himself continued to retain ordinary jurisdiction (ie., apostolic mission) for the Diocese of Campos.
What did end up happening was that 40,000 Catholics in Campos refused to sellout, and continued to seek out the traditional priests of Campos who remained affiliated/allied to the retired Bishop Castro de Mayer (creating a sort of diocese within a diocese, but only de facto, not de jure).