I''m not having pocketfold invites and I''ve never received one, so I''m not sure what most people do. What dimension exactly are your pocketfolds? Perhaps we could help you search for envelopes that would work.
Jaders -- I think that the original purpose of having the inner invite was so that the dirty envelope that went through the mail could be removed before whomever collected the mail delivered it to the lady/man of the house, and so that you could clearly indicate who is invited. The first isn''t as much an issue anymore, although you still need to be able to indicate who is invited.
As far as guests living alone but with a significant other, invites should be sent to each individually at their own address.
If you''d like to invite someone with a guest, you could somehow indicate it on the response card or include a small note about how they can feel free to bring someone if they''d like. If you''re having a fairly small wedding, you could also call them after they likely received the invitation. As "Guest" isn''t the name of the person attending, you''re not really supposed to include it on the outer envelope. One warning -- if you''re having individual seating cards, you might want to find out the names of all of your guests so that you don''t have a place card reading "Ms. X''s guest."
As far as some things that you would normally indicate on the inner envelope (Mr. and Mrs. Smith, Johnny Smith and Betsy Smith), you might be able to indicate them on the outer envelope. I''ve read that you can include children on the outside envelope and I''ve read that you shouldn''t ever include them on the outer envelope, so I''m not sure which one is "correct".
This is just from memory from what I''ve read, so I could have misremembered some of these things. I hope that this all helps.