Drop it in my inbox and I'll see what I can do :)

There are a few in Mahatun Plaza right next to Ploenchit BTS station

You're very welcome :) I hope it all works out for you.

No, sorry. Never heard of any family tree thing. I reckon you should still talk to a Thai lawyer. Tell them the whole story (maybe substitute the phrase 'false name' with 'different name'?)

I'll bet it's not the first time they will have heard of such things and the main thing is to establish your mother's Thai citizenship, not whether or not she used the right name or not.

It might be worth sending these guys an email

By the way, it won't save you hassle, it WILL BE HASSLE lol

But once it's done, you're all set for the future. Anyone who's mother is Thai is also Thai. That's the basic premise. Proving it, in cases like yours, is where the hassle is.

Ok, so the search would begin in the Amphur (district office) in Khon Kean. Thai bureaucracy is sometimes annoyingly difficult to deal with, although it's quite thorough, and they are inclined to require people to physically attend in order to get things like this done. You might need the services of a Thai lawyer if you wanted to get this done from the UK. You will need as much information as possible. Her full name, date of birth, the area of Khon Kaen where she was born, and then take it from there. How's your Thai language skills?

There's going to be a bit of detective work required, but in the long run it will be worth it.

The fact that she had an ID card means that there are records of her birth, and the fact that she is a Thai citizen. Tracking that all down is another story. Where was she born?

If your mother is able to prove her Thai citizenship, then you will also automatically be recognised as a Thai citizen yourself. You also will have to prove that, but that should be straightforward enough (your mother is Thai, has proved it, you can prove that she is your mother) and then you can come and go to Thailand whenever you wish and not require visas, work permits etc.

If I were in your position I would have the French document translated into Thai before I left Thailand. The French embassy in Bangkok should have a list of approved translators.

If they don't need it, then you may have wasted a few baht, but if they do, and you don't have it..... a lot more baht!