FI and I decided that we weren't going to invite people we weren't super close to, to easily make a small wedding of about 60 people. Since I have two best friends and a very small family, and he only has one best friend and a decent sized family, this is no problem. We are at 46 invites (but not quite done adding people) and would like to allow the teenagers to bring guests, because we remember what a "drag" it was to hang with family for extended periods of times in those awkward ages.
How do we address an invite to a family who has children that we are allowing to bring a guest?