I'm not certain what you are asking for here. You appear to request that NCL allow you to "step up" to one of their sister lines. You mention Regent, I assume you mean Oceania as well. But what would you gain from a "step up" unless there is some sort of exchange of loyalty perks, which there is not, as far as I know.
We have been cruising for years on Princess, Regent and HAL. If I decide to book on Cunard, for instance, and mention my super loyalty Captain's Club status with their sister line, Princess, it means absolutely zero. I know, I tried that. Same goes for Carnival, they could care less what perks I have earned with their sister lines, Princess or HAL. As for the NCL family, the same level of indifference exists there, if I mention that I'm a Regent "Gold" when talking to NCL or Oceania, well, a free cup of coffee isn't even forthcoming. In short, there is absolutely no difference between me, as a old time Princess loyalists, going to Celebrity to get rates etc than there is when I go to Carnival, Cunard or Seabourn.
For quite some time now the subject comes up on Regent forums mentioning rumors that perks from Oceania or NCL might be good on Regent. That usually brings on quite an exchange of opinion, most argue against the exchange being on a one for one basis. Nothing ever materializes though but I've often thought that it would be nice to use my Regent perks on Oceania if they could come up with some sort of formula to make one line's perks commensurate with another's.
I know very little about the Royal Caribbean family but understand, from these forums, that they do have some sort of perk exchange.
You mention New York, since all of these lines serve New York at one time or another on various cruises I guess you want, say Regent, to base a ship there or at least make it an embarkation-disembarkation port? We have cruised to/from New York before, disembarked once on Princess and disembarked twice on Princess. Remember, Regent has only four ships and Oceania six, all are in the "small" category.
Anyway, I think I agree with you, just not sure what for.