well,since 6 members are shown (Young Xehanort,Master Xehanort,Xemnas,Ansem SoD,Xigbar and Saix),i think the other 6 members in the new Organization XIII that Young Xehanort meet besides Sora could be:

 

(these are the choice so it's not fully confirmed...)

 

1.Demyx

-Young Xehanort can meet him before his demise at KH2

 

2.Luxord

-same as Demyx

 

3.Larxene

-same as the other two

 

4.Marluxia

-don't know if he will join or not because he want to betray the organization himself

 

5.Terra-Xehanort

-he could meet him when Terra-Xehanort was lying on the ground at the Radiant Garden after fighting Aqua or at the Keyblade Graveyard when he lying on the ground after he defeated by Terra's armor or before the X-Blade explode the entire Graveyard

 

6.Vanitas

-Young Xehanort could be meet him at Badlands though or another place i guess...

 

7.Sora (Re:COM Timeline)

-i think this could be happen when Sora's memories are gone including his memories about Kairi and Xehanort could have an avantage to make him join the Organization.

 

8.Riku-Ansem (KH1 Timeline)

-Young Xehanort can make Riku to join the group since Riku was possess by Ansem.After all,Riku-Ansem could be useful since he has the Keyblade of People's Hearts...

 

9.Riku Replica

-who knows?maybe he can join the group and i think they will meet before his demise by battling with REAL Riku

 

10.Ventus-Vanitas

-it could be possible since he has the X-Blade and make the Organization's job easier to get Kingdom Hearts

 

i know some of the choice are as bad as you think,but this is my opinion,so what's your choice?and thanks to read my theory....

Edited August 18, 201213 yr by Hazimie

I'm not sure. Good thing Sephiroth didn't go up against Hagrid then.

 

Am I the only one thinking he'd get lost in his beard...

My 6 would be:

 

Vanitas

Riku/Ansem

Terra/MX

Luxord

Riku Replica

Xehanort (apprentice)