thank you for your detailed, Informative reply. The DTV idea gives me another line of inquiry at the immigration office. I suspect 2 standard retirement visas will end up being the easiest solution but I will enquire about the DTV. I don't know how widely that option is used in Eastern Isaan, where I live.
thank you for your helpful input. Very insightful! I am thinking that I'm probably not the first retired farang whose parents would like to come and live with them. I was hoping that someone who has been through the process before could share their knowledge. I will of course be visiting my local immigration office regardless of what tips are shared.