In case anyone is researching, I think the word is Nethinim not Nephinim. Hardly mentioned since it first appeared as a doctrine. The WTS tends to let some die by not mentioning them again.
I remember that. Mid 90's. It was not too long after the "generation" change that made it completely open-ended and squashed any hope of the end coming before the end of the century. The Nethinim being "other sheep" helpers who would start taking over for the F&DS was mentioned in like one WT study article. Got a lot of tongues wagging about what it could mean. And then no one heard about it again.