I think that in the secret movie for FM+ they are on the darkness side of the worlds and the Kingdom Hearts that OEM summons is not in fact The actual Kingdom Hearts but the darkness realm side of it which is linked to the light realm Kingdom Hearts which is how ******SPOILER****** Sora and King Mickey meet in the end of KH1 on both sides. also the reason King Mickey has Star Seeker I think is, you know how Yen Cid was Mickeys teacher? well, i believe that that was Mickeys first Keyblade and gave that back to Yen Cid for Sora because Mickey had found the Keyblade for the dark realm and King Mickey needed that Keyblade to close Kingdom Hearts *SPOILER* at the end of KH1, and Sora needed Star Seeker more thatn Mickey. Also this trailer takes place during Sora's adventure in kingdom hearts 1 but it happens in the dark realm and the FM+ trailer is for the next KH game which is confirmed to be on a portable system it will be KH 2.5 (actually it will not be numbered as Nomura stated) or this is for the 3rd part of the story and my thought is not valid.
Thanks for reading!
Thanks for reading!