I have a teenage daughter in Thailand whose mother cannot handle money. I am also 77 years old and last year I posted a request for advice similar to yours. I got lots of advice like you are getting regarding hiring an attorney. If I cannot trust my Thai wife to hold money in trust for my daughter can I really trust an attorney?
I have life and health insurance in Thailand and a simple question regarding a $200,000 trust paid out over ten years resulted in near constant high pressure sales from the insurance company. I decided not to purchase the trust since the terms were so one-sided in regard to profit for the insurance company.
There are immediate trusts sold in Thailand by insurance companies. Banks are no help and offer nothing in my experience that addresses long term payouts to minors in particular. If one is under 18 one needs a guardian. This is the problem- finding a guardian who puts the interest of my daughter ahead of theirs.
As much as it pains me to say it, there is no one that can be trusted to NOT spend large amounts of money in Thailand. This includes family members even in the best circumstances. I have seen many cases where money issues have split families into warring camps.
Money can destroy lives just as it can improve and benefit lives. My health scare of a year ago was resolved but the problem with money and my daughter still torments me. Good Luck....