No mystery here. They are all male jewish virgins, just like scripture says. So, why all the muck and fuss?
The WT has made a big deal out of the fact that Ephriam and Dan are left off the list of tribes in Revelation 7. Ephriam's father Joseph appears in his place. The priestly tribe of Levi (who had no land inheritance) appears in the place of Dan.
So, instead of trying to find out why, the WT just declares the whole thing to be symbolic and surprise, surprise, the scriptures are really talking about them and their origanization. I will show why this is unfounded and offer a far more plausible explanation..... an explanation that does not require you to worship follow Watchtower.
If you will recall, Joseph had an amazing life and was deprived of fellowship with his father for decades by his brothers. He was also only one of two sons from the beloved wife - Rachael.
So, instead of Joseph receiving one portion of the land inheritance along with his brothers he received a double portion when his two sons Ephriam and Manasseh each received a portion. Normally, only the first born son would receive a double portion. But, Jacob gave the double portion to Joseph, through his two sons.
So, the tribe of Ephriam and the tribe of Manesseh together constitute the tribe of Joseph in a sense. The tribe of Levi was a priestly tribe and did not have a land inheritance. So, by adding Ephriam and Manesseh in place of their father Joseph (minus Levi), it still equalled12 tribes.
Now we get to the Revelation 7 list of tribes. We notice that Dan and Ephriam are conspicously missing and Levi (who never had a land inhritance but were still a tribe) and Joseph (father of Ephriam) are listed.
There is a very plausible explanation for this:
Why are Ephraim and Dan missing from Revelation 7:4-8? The answer is not stated specifically in Scripture, but most likely it is because these tribes led the rebellion against the Davidic kingdom that resulted in the division into the northern and southern kingdoms. The second likely reason is that these tribes immediately led in the establishment of false worship and abandoning the worship of Yahweh.
So, these two tribes are not allowed to participate in heralding the impending birth of the Millenium Reign during the great tribulation because of their previous apostasy and rebellion.
But when we look at the land inheritance that will be portioned out in the future Millinium Kingdom, the original land recipients are listed as usual.
See Ezekiel 48 prophecy about the tribes of Israel in the Millenial Kingdom.
So, Dan and Ephriam are temporarily left off the list of tribes who will be witnesses of Jesus during the great tribulation because of their rebellion and apostasy, but they do receive a land inhitance during the thousand year reign after it is over.
Calling something you don't understand symbolic is a lazy man's theology. The explanation above is far more plausible than the WT explanation where they are the 144K listed in Revelation instead of what scripture plainly says.