@Cassius *********
you need an appointment at MFA also.
I would recommend using an agent for this service (I never use agents normally).
Without an agent unless you are very organised, you will end up back and forth to Bkk.
Someone is recommending one in the thread, it might be worth seeing how much they charge.
We were offered this service when getting our documents translated at the MFA and I refused, I wish I had accepted their offer as it was not a lot of money and would have saved us a lot of time, travel and hassle.
At the district office in Bkk you will also need an interpreter and witness. The agent also organises this.
Whatever you decide, I wish you and your wife lots of happiness.