How to you include invitation only verbiage on an invitation?

It is a party that you need to receive an invitation to get in.

If you are married or engaged, your significant other is supposed to be invited. (If you have only recently become married or engaged, it's okay to calll the bride and say so.) Otherwise, you go...

"& Family" is not printed on the outter envelope. It's included on the inner envelope or RSVP card.

Invitations are small white pieces of paper, they were used to invite the crowds of people that attended Birthday, wedding, bridal shower, party....

You should generally have an RSVP card and a reception card insert explaining the reception details. You can look at online wedding invitation stores, like the one linked in the related links...