There was never any doubt that Nawapooh Sae-tang, the grandson of the late Bangkok-born artist Tang Chang, would inherit the family business of protecting and promoting his legacy. “My father had told me from a young age that as his eldest son, I would have to be involved in the running of the estate,” he says ahead of the May 1 opening of the Tang Chang Private Museum in Nakhon Pathom, an hour outside the Thai capital. It might not have been his choice, but Nawapooh has blossomed into a...