My mom insisted that my grandpa's side is Teochew, but his ancestors had Hokkien surnames
I'm Thai but my mom's side is mixed Thai-Chinese, not much is known about my Chinese side's oral history, other than that they migrated through Laos unlike the majority of Teochew people, who travelled via junks leaving Southern China for destinations like Malaysia, Philippines and Indonesia. Their ancestral surname was "Ooi" or "Sae-ui" in Thai (Sae being a common Chinese surname prefix in Thailand), and this is where the issue came
Ooi is only found in certain dialects of Hokkien, and if it was Teochew, it would've been "Ung" or "Sae-eung", which makes me wonder on what could've lead to this, but i only have a few theories
They were Hoklos that once lived in Chaozhou, hence the confusion that they were Teochew when one of my ancestors migrated on land towards Laos, and eventually Siam (Thailand)
One of my patriarch was Hoklo, and the matriarch adopted his surname, hence the Hokkien surname and not the Teochew one
They were Hoklos but identified themselves as Teochew because of the environment they lived in, as parts of their family (which included my grandpa and his siblings) would later relocate to Bangkok, which is majority Teochew and Cantonese in the community, and to better fit in, identified themselves as Teochew
But i can't really confirm, because my Chinese side of the family was effectively cut off from communication ever since my grandpa died, leaving me to piece everything myself and by what my mom says. However, i'd like to know if it's a common thing or not for an ethnolinguistic group to have the surname of another ethnolinguistic group, and this would be the one closure that i want for now