I would suggest a similar solution like @STR_Warrior
settings.ini:and allow to create custom portals via plugin.
Default value for "default" is "false".
settings.ini:
Code:
[worlds]
[WorldName]
default=true
nether=Dimension _Nether
end=Dimension _TheEnd
[2ndWorld]
nether=cookies
[3rdWorld]
end=banana
Default value for "default" is "false".