I've never heard of a famous sister writing a rec, but Kristin Chenoweth is doing the ribbon cutting for our new house at Alabama in August. Maybe she'll make some contacts and get asked next year!
I've checked her address in our member search before, and she has her publicist's address listed. I think it could be pretty tough to get in contact with anyone famous to even ask. You'd definitely have to know them personally, like your friend.