We always had Anna (elder brother), Thanthai (father), Thatha (Gandhi), Mama (though in the north he is Chacha- Nehru). We also have Amma. Now we have Anni too. Mrs Besant! I have seen the name metamorphosing into Basant/Vasant and at times into Pleasant and Peasant but Annie becoming Anni!
This isn’t as bad as the other ones.
If you read it in English, yes. The Tamizh script does not establish the lady’s relationship to us as our sister-in-law (unless we are attuned to the way they pronounce words in soap operas) because I see the two-swirl ‘na’s there (as in annai kastUrbA–and well, Gandhi was thAthA!).