I've now posted my "Many-One Identity and the Trinity" paper. In it, I consider whether accepting Strong Composition (the thesis that an object is numerically identical to the plurality of its parts) will help the Trinitarian (who, after all, is wanting 3 to be 1). I claim it the thesis doesn't give us any options we didn't already have. (In fact, due to worries concerning monotheism, I think that there are reasons for a monotheist Trinitarian to reject Strong Composition as identity when supplemented with Fregean counting.)
Comments would be greatly appreciated!