i got a idea how you could lore wise explain why there are slideshows telling the courier adventurers and choices in the wasteland the ncr kidnapped (if sided with independent, house ,or legion) or brought back to celebrate (if sided with ncr) to the ncr embassy in a guarded room to investigate the events that lead to the couriers rise to power two events could happen 1. if sided with the ncr a diplomatic representative of the ncr will walk in telling the courier they have chosen him/her to be the governor/governess to run new vegas for the ncr and help secure it as a stable state and they are there to assist in any matters that might arise as adviser 2. if sided with house,legion,or independent a fanatic fan of the courier blows open the door taking out the guards to stage a rescue for the person they think should be in charge and help with anything the courier wants the ncr so embarrassed by the event they cover up the incident so as to not effect any relationship you might have or want to have with the group thus the take over of New Vegas begins