Problem Multi world?

[fenukottero]

Hello dude, I have a FTB server for with friends and me. Is it possible to create, for example, a portal and, through this portal, going to a new world without mod? a vanilla world? Some friends wanna join the server but they like vanilla!

 

[DZCreeper]

Use Mystcraft. Just choose some vanilla biomes and write and stable age for them to explore, there will still be modded world gen, but they can ignore that or find a new server.