The website for Isaan Lawyers is udonlawyers.com — perhaps they can perform whatever service is needed.
I have noticed in the past that the subject of local lawyers arises from time to time on the UdonMap forum — threads such as this from two years ago: Lawyer in udon Thani. I believe that the “Sebastian” mentioned in that thread is the one listed at Korat Lawyers; and also at Isaan Lawyers. Certainly check the forum for other lawyer-related threads — they are there.
Somphol & Associates Law Office make the claim “Serving Udon Thani for 25 Years …” on their website udonlaw.com.
When I checked out the site Thailand Lawyers, a chap by the name of Dusit Phomsit was given as their agent for Udonthani (as of an October 29, 2010, update). His name also comes up on the Thai Visa forum thread begun last October titled Lawyer/Legal Services In Udon Thani.
Possibly worth consideration is Isaan Law Online: Whether you need an English speaking Thai lawyer in Roi-Et, Nakhon Ratchasima (Korat), Buriram, Surin, Khon Kaen or Udon or Ubon Thani, we offer reliable legal and contract services for expats online. We offer an alternative to traditional legal services in Thailand and provide reasonably priced professional licensed legal services and documents online. Why pay more to a local lawyer if you can get an experienced Bangkok lawyer online? Discover the advantages of using an online provider for all your legal needs in Thailand and at the same time save on travel time and save on lawyer fees.