what do you meant with papers from the school? the embassy took all the docs when you apply for your visa.. from your side is basically the same, ie : passport copy, photos, residence certificate/house rental agreement, birth certificate legalized by your embassy, fee 1900B, bank statement+letter, bank book. but then again, each immigration and each officer has different policies (mine is chiangmai).. so the best is to talk to the school, they will tell you what and which.
first you need to tell the school like 3weeks before expire date.. and they will prepare the docs and tell you what they need from you. definitely 500k in bank account minimum 3months before you extend. next you will get 1year extension. (if your daughter in school, not language school)
well i normally extend my visa at least 1 week before the expiration date.. i had 2 ED visa last 2 years.. the officer will count 90 days from the expiration date so no worries but yes better avoid coming 1 day before long holiday. oh i recently extend my son ED and my nonO on 17feb for expiration date 3mar.. you can notify your school asap so they can start processing the documents.
3 months minimum before you apply for extension. as far as i know you need to keep you balance minimum 500k. the officer will check your book bank when you do the extension.
just 1 question, you said only birth certificate, chikd house book and 400k baht to get the visa. No need legitimation from the court for being the legal father?
yes your kids can get nonO based on your ED but you need to tell your school and ask for a letter from the school stated your minor children will accompany you in thailand. the docs for them are simple: letter from school, birth certificate, passport and visa fee.. but need to check with thai embassy of your location thou..(not sure about your husband)