I own an apartment since quit some time in Bangkok.

My (longtime) girlfriend would like to register her residence in Bangkok, so she doesn’t has to travel to her hometown for any administrative issues.

This, apparently can be done by requesting “a blue book” that goes along with the apartment, in Thai, sam now tambia baan and put her name in it. Second, she requested also to sign her in this blue book as “boss of the house” in Thai, chaw baan.

What if I register also her brothers and sister in the same "blue book" ?

My questions are, what are the legal implications to get her name into the blue book, and to register her as Chaw Baan ?

It is my understanding that an an equivalent "yellow book", that I dont have is available to farangs only. What is the need for it ?

The advantage for the brothers and sisters is that the creditors will come to your place to collect debts from credit cards, unpaid mobile phone bills, car loans etc...

My (longtime) girlfriend would like to register her residence in Bangkok, so she doesn’t has to travel to her hometown for any administrative issues.

Believe all districts are now online so this is becoming less of an issue. ID cards can be issued anywhere. Home register is not required for most things (but old ways die hard so this can still be a problem). I would suggest legal advise before you do this as it might be setting you up for claims on your property later (don't know that; but I would be careful).

You say that you "own an apartment" - do you mean that you puchased a condominium unit? In that case, you should indeed have a tambien bahn,listing you as head of household. If you do not have such a document, then you need to reexamine your "ownership" status.

Good luck!

Indo-Siam