A: If the invitations have gone out there's nothing much you can do. You can't call them up and un-invite them to the party.
You need to schedule a time to talk with both set of parents about the size and style of wedding you and your fiancÚ want. Based on the size of wedding you want and the amount of people that your reception site can hold, you need to let both sets of parents know how many guests they can each invite—including relatives and friends.
If the space allows more people, you may now have to invite these extra guests, or ask your parents to spread the word that the bride and groom have decided to hold a more intimate wedding with only immediate family and close friends.
Here's a general rule to follow: If you send an engagement party or bridal shower invitation or a save-the-date card to anyone, you will also have to send them a wedding invitation.