You might try The Butler Society in Kilkenny. Membership fee to any Butler is $20US. They also host a Butler Rally every three years at Kilkenny (Butler) Castle. The next rally is in August 2015. Anyone with the name Butler is invited. 250 - 300 Butlers from all over the world are expected to attend. There is also a Butler Society of N. America but I haven't been able to access their web page. There is a Butler in California who took over the Butler news letter. I believe he publishes it bi-annually.
Good luck,
Michael Butler