As I said, the information here
is a little better, if you can read Japanese.
The post-war organization has no real connection to any major Aikido organization that I am aware of. There's nothing wrong with that, of course.
Just to make this clear, when Aikido was first named as such (not by osensei), O`sensei, had to give it a name so that it would be accpeted as a traditional Budo by the Japaneses gouvernment, this is achieved through, Dai Nippon Butokukai.
The DNBK, authorizes teaching & certification in traditional Japanese arts including Kobudo, Aikido, Iaido, Kendo, Judo, and other tradional arts from Japan.
Head of DNBK is, His Royal Highness, Sosai, Higashi Fushimi, Jigo, the chief abbot of Shorenin Temple. He is a brother to late Empress Kotaigo of Emperor Hirohito of Japan. Vice Governor, Fuku Sosai is his son, Higashi Fushimi, Jiko, he serves as the Shinmon of the Shorenin Temple.
Many of today`s exponents of Aikido within Aikikai, are also members of DNBK, including Hioaki Izumi Sensei, 6th Dan Aikikai, Dan graded also in Kendo and Iaido.
Post WW2 or not, many people still in Japan today still consider DNBK recognition, as one of the highest authority on traditional Japanese martial Arts. And many practitioners from Differetn arts Are members.