if you are not going to use an Agent to get a Retirement Extension of Stay at your local Thai Immigration Office = obtain your 1–Year Extension of Stay yourself, then you need to open a Thai Bank Account and get ฿ 800,000.- Thai Baht ( ฿ 800k Baht) in your Thai Bank Account and have that in your Thai Bank Account for at least 2 months before applying for a Retirement Extension at your local Thai Immigration Office
Did you get a Non–O Retirement E–Visa from a Thai Embassy/Thai Consulate outside Thailand or did you get a Non–O Retirement Visa ink Stamp from a local Thai Immigration Office inside Thailand??
Perhaps it's more straightforward to just modify your travel plans to arrive in Thailand a week later and then have sufficient time to transfer all of your Thai immigration stamps into your new passport
Well, what country are we talking about here? because every country his different laws, regulations, and policies for different family members and immigration status of that country
also, for nearly all countries, the age of the child is an important criteria to consider