If you are a low income person have a serious think about your plans. As non Thai your son will not qualify for free education so you will have to pay for private international schools. Health care is not free in Thailand, while outpatient care is inexpensive, if you need hospitalization it can be cripplingly expensive.
I use HH immigration never a problem with multiple transfers as long as the total is 65k+ per month. I do make it easy for them by doing a seperate sheet listing all transfers and highlighting the transfers in the bank statements.