Not an anime analysis but fic idea:
Every character that reached Permet score 4 and up, weither they died while linked up or not, created an echo or a copy of their conciousness that exists within the data stream of Permet. This latent data, which is normally unobservable by operating systems, could perhaps be uploaded/carried from machine to machine as long as there is permet and a link present to carry said data.
What I'm trying to say is digital Daddy Nadim being found and woken up by Suletta within a discarded component of the Aerial after a copy of his data was uploaded during the prologue after he used Permet score 4 and saw the digital sphere. (Cause OG Aerial is a refitted Lfrith ala episode 18)
Now also include some detective of both Nadim and Suletta working together trying to figure out Eri and Elnora's plans.
Also the reason why Eri hadn't found Nadim within Aerial is because Eri was a part of the main OS and Nadim was dormant/fragmented. Weak in comparison to her who likely reached a way higher score and integration.
Like Eri this is the real Nadim, but potentially other characters who died from Permet data storms may be real too, such as Sophie. Potentially a ghostly copy of Elan 4 is around somewhere also but this one is really a copy because it might be more limited and because Elan 4 didn't actually die from a data storm like Nadim and Sophie.
I just want good dad Nadim to give Suletta some comfort in these trying times, damn it!