I heard about this dialect, in Mandarin it's Chaozhou, the people of this city is known as good businessman... does your father make business in Thailand?:) By the way, why he decided to move from China? Or it was before him by grandparents? Can he speak Thai?
That's a pity that you can't speak Teochew:) I saw one Thai film, the girl there can speak only Thai, but her grandmother speaks only Chineese, so mother used to translate:) do you have something like this in your family?
Of course, for foreigner is useful to study Mandarin:)