There is another distinction, between the Yibbum and Gilgul, and this is what we described at the beginning of this explanation. And that is when a person is reincarnated via the secret of Yibbum (not via Gilgul), it is as if the first body never existed (because it died without having any children). So the Nefesh and all of its parts are born into the child created via Yibbum, as we already described.
We find that this [child] is a new creation (a new 'building'), literally, and therefore it can have reincarnated into it [with the Nefesh] also the Ruach, and the Neshama, and all three of them can [immediately] be in one body [rather than having to come together through multiple gilgulim, one after the other]. However, this does not happen all at once; rather, [he gets the Nefesh at birth,] and when he merits it and does mitzvot which would merit a Ruach [e.g., when he becomes Bar Mitzvah], a Ruach enters into him, and so too with a Neshama, just as we explained above at the beginning of the entire explanation about the birth of an Adam (a person) in this world when he was literally new, just as is described in בסבא דמשפטים, that he merits a Ruach in the second reincarnation, and then the Neshama in the third reincarnation, etc. Therefore, in a birth resulting from the secret of Yibbum, he is like a brand new creation (his first life), and he is able to receive all three of his Nefesh, Ruach, and Neshama in one life, according to his actions as we already explained: