What is the process for obtaining a 60-day extension on a Non-O visa at the Chiang Rai Immigration Office?

Info sharing: Chiang Rai Immigration Office

Got my 90 Days Non-O visa from the Royal Thai Embassy in Singapore (as a Singaporean). Went to the Chiangrai Immigration office today to obtain my 60 days extension based on Thai Child.

Documents required:

1. Photocopies of Passport, Entry Stamp + Visa Page (90-Days) + Arrival Card

1. Photocopies of Child's Birth Certificate + Tabien Baan

1. Photocopies of Mother of Child's ID + Tabien Baan

1. Filled Up Extension form + Acknowledgement form for not overstaying + Acknowledgement form for the fines if overstay

Original documents were not required. TM30 was lodged online when i arrived at Chiangrai home. Officer asked me why I lodged the TM30 a week later from my arrival date. I informed that I arrived via Bangkok and had stayed in Bangkok. Had to show my arrival ticket (which I show my electronic copy) and my Agoda bookings to verify that I was staying in a hotel during the period which I did not lodge my TM30 upon my arrival. All was fine then. Whole process took 30 minutes. Easy day!