This was a really fun surprise to set up, & it's also low-cost & only requires as much effort as you want to put into it. Obviously, I can't guarantee that doing the same thing I did will get you the same results, but I will share the process I used just in case anyone is interested!
I had seen in several Pinterest posts that people had gotten congratulatory wedding letters from Mickey & Minnie, the POTUS & FLOTUS, & JK Rowling just by sending them a wedding invitation. I thought those were all fun ideas, but I wanted to expand on that & personalize letters to people Mackenzie really admired.
I had a limited amount of extra Save the Dates, & I knew some people were supposedly guaranteed to reply, so some people got Save the Dates, some got personalized letters, & some got both. In the letters, I wrote specifically to each person about what they meant to Mackenzie & asked them to write a response, if they had time. I tried to be very polite & genuine in each one. I also sent a self-addressed, stamped envelope with each letter to make responses as simple as possible for the receiver (Remember to use international postage where necessary!). I will include below the addresses of those who did respond, & photos of the letters! I will add that both Lin-Manuel Miranda & Sara Bareilles used the envelope I sent, so this did seem to help! I also sent these out months in advance (one round in January I think, & another round in March), & it took about that long to get some of the responses back. Allow at least 2 or 3 months for responses if you're attempting to do this! Sara Bareilles was in the later group, & we received her reply during wedding week.
So, here is the list of people I sent letters to, with bold if I got some sort of reply. Below tells the type of response received:
Sent Save the Dates to:
Cinderella & Prince Charming (Disney World) (response was a postcard from Mickey & Minnie)
Mickey & Minnie Mouse (Disneyland)
Sent Save the Dates & Letters to:
JK Rowling (got a letter addressed to Mr. Sydney saying she doesn't reply to fan mail. Ha!)
Senator Bernie Sanders
Lin-Manuel Miranda (personalized, handwritten postcard with photo)
Sent Letters to:
Hamilton Cast & Crew
Sara Bareilles (personalized, handwritten letter to Mackenzie with a shout-out to me at the end)
Another thing that we did: On our last Disney trip, Taryn & I picked out a cute Disney wedding card at Target, & I took it with me throughout the parks. Laker & I went to TONS of character meet & greets, & had most of them sign the card! We actually had to start being choosy about who got to sign because the card was getting so full. This was so fun, & lots of the characters had little messages they asked me to pass along to Mackenzie. Cinderella asked all about the wedding plans, Peter Pan wanted to make sure they never stop going on adventures, & Fairy Godmother was so excited that Mackenzie was "one of their own," since she was part of the DCP.
Taking a card for characters to sign can be a great surprise for anyone with an upcoming birthday, or for a Valentine's or Christmas card - if you're sneaky enough to keep it hidden from the receiver!
Mickey & Minnie Mouse
PO Box 1000
Lake Buena Vista, FL 32830
c/o Bloomsburg Publishing PLC
50 Bedford Square
London WC1B 3DP
4768 Broadway Unit 743
New York, NY 10034
Sara Bareilles (I think this is the address I used...)
Paradigm Talent Agency
360 North Crescent Dr.
Beverly Hills, CA 90210-2500