At Team B's theater show on April 14, two new AKB48 members were revealed. Taniguchi Megu and Iino Miyabi who were tentative Kenkyuusei appeared as backdancers at the show and were promoted to full Kenkyuusei status. They are officially part of the 15th Generation.
Something like this happened before: Okawa Rio and Tatsuya Makiho started as tentative Kenkyuusei too and were then promoted to 15th Generation Kenkyuusei in October last year.
At the AKB48 Group Daisokaku Matsuri in February all Kenkyuusei left were promoted which meant that in the new team system AKB48 would have been without any Kenkyuusei. Now they have two.
Update: Their official profiles are up now: