Think of it as two separate processes, heavily interconnected, proceeding at the same time but not necessarily at the same speed - the evaluation of the candidate’s application and the elected official nomination process (external) and eventual charging of an appointment to a nom authority (internal).
Each application is looked at and evaluated on its own merits, to determine if the candidate is fully qualified. That could happen not long after the application is submitted, or anywhere along the path. It could happen well before the slate of noms is submitted by the elected official. At some point, and the combinations are endless here, if USNA decides they want your daughter, and she is fully qualified, they will look at her nom situation, and see where they could charge her. It could be easy, or it could be dependent on her fully qualified competition on her nom slate, of her status versus other fully qualified applicants in the national pool. They could be waiting to find out if a candidate ranked higher than she is on the slate will be medically cleared or not. There are many, many factors in putting this complex jigsaw puzzle together, systematically, as they build out the class.
In your daughter’s case, a late nom, no matter what, is manna from heaven. She’s in the game. There could be many scenarios in play here. Maybe no one else on her slate fully qualified, so USNA went back to MOC and asked for a nom to be assigned to your daughter. She is clearly in play, appointments are still coming out, you don’t know when her app was first evaluated, you won’t ever get a glimpse behind the curtain - so patience, hope and a positive outlook on alternate plans are the keys to surviving this.