Can I submit the Kor Ror 22 form for a marriage visa anywhere in Thailand or only in Chiang Mai?

If you were married overseas.. meaning not in Thailand.. then the first step is to get a copy of the original marriage certificate certified by the Embassy of the country where your marriage took place.. for most people that's likely to be their home country.. but you could have had a vacation style wedding of course.. so, if you're British and got married in England the British Embassy in Bangkok would need to authenticate the marriage certificate in this manner.. the second step is to take this, along with a translated copy (in Thai) to the Ministry of Foreign Affairs in Bangkok for certification by them.. but you need to complete the first step before you can move on to the second step.. and given the complexities and inconvenience involved it's best to use an agent who knows the ropes and can expedite this for you.. we are in CM and didn't want to waste our time and energy traveling to Bangkok in person.. so found an agent that could do everything and produce the requisite documents..which took around 2 weeks from start to finish and needed us to attend the final document collection at the International Convention Center in CM to reduce the wait by nearly a week.. the fee was just over 5,000 baht in total.. and they threw in a translated copy of my passport for good measure.. which wasn't needed by the Amphur to register the marriage but i guess it might come in useful sometime.. but be aware that the Amphur may try to retain the original certified copies.. ie. instead of simply taking copies of them for their records.. which is outrageous imo since you may need to use them elsewhere in the future.. and don't want to have a repeat of the hassle and further expense.. i pushed back hard and told our Amphur they could only keep them if they gave me a legal undertaking to return them if i needed them.. or alternatively, agree to pay an agent the necessary fee to produce another set for me.. and after deliberation and consultation with superiors they backed down and simply took copies which they certified for themselves!

You should be able to do it anywhere I believe. That's supposed to be the easy part. The difficult part is usually getting everything legalized before going to Thailand and then translated for the MFA.