So yesterday when I checked the mail I had 3 RSVP envelopes woo hoo!! I opened 2 of them up, declines boo!! but the third had no return address label and they didn't write their names on the card so I have no idea who it's from.

Luckily, I only sent out the first 20 before I realized I could get into this predicament and then started writing in invisible ink on the back of the response card the names of the invitees.
So it looks like I have some research to do, but thankfully not a whole lot!