I believe a few years ago within the UK there was a move within the zoos there to move to transfer any and all small flocks of the Chilean Flamingos to other zoos that had larger groups to give them a better chance of breeding success!
That’s a great example of the cooperation all zoos should follow for the good of the species.
Given they were down to 16 adults/founders when Auckland Zoo’s flock first successfully bred in 2014, they’ve achieved outstanding results; but it’d be ideal if there was another holder in the country that could swap around non breeding birds with them to see if a change of available mates or even environment brought about breeding.