We had moved to Kolkata in 2000, so that my kids can get to know their grandparents and learn Bangla and Bengali culture. My wife by then was fluent in Bangla, but the kids were learning a new language. As my wife and I weren’t comfortable in each other’s mother tongue earlier, we used to speak in English initially ,and the kids grew up speaking English at home.
Their Bangla was heavily accented and was being constantly corrected, especially as, like all Bengali kids, they were learning Rabindrasangeet.
One rule that they understood was that the first vowel of the vernacular alphabet has a O sound in Bangla as against the A sound in Hindi.
Those were the Doordarshan days, and we followed an excellent series called Neem ka Ped.
My 5 years old daughter, very seriously commented during the telecast,
“ They are saying it wrong! It should be Nom ke Pod in Kolkata “
By the time we returned to Delhi a few years later, they were both comfortably trilingual.