There was this post on YouTube by Sri. Yesh Prabhu who apparently had been learning under Sri. T.N. Bala for many years. In this post, he mentions how T.N. Bala became Mani Iyer’s disciple. I will simply quote his post here.
“I am so happy to see that Sri Madurai Mani Iyer is respected and so revered even now, after all these years of his passing away. (He passed away on June 8, 1968). Sri Mani Iyer was my guru’s guru. My guru, the late Sri T N Bala (composer of the famous kriti Vilaiyada idu nerama? in Shanmukhapriya raga), was a very senior disciple of Sri MMI. My guru told me how he was chosen by Sri MMI to be his shishya: Sri MMI was sitting in his yard one Sunday morning, listening to Madras AIR. Two young boys were singing Shree Muthuswami Dikshitar’s kriti Surya murthe in Sowrashtra raga. Impressed, he called the radio station to find out who the boys were, and was astonished that the boys were the sons of his neighbor across the street. He then approached their father to express his wish to teach the boys. Their father was only too happy, of course, and consented. Occasionally, after my lesson, Sri Bala sang for me, imitating Sri MMI’s voice, a Navagraha kriti or a Navaavarana kiti. It was as if Sri MMI sat in front of me and sang; and it was an amazing experience! I have learnt Carnatic vocal from Sri T N Bala for more than 29 years. YeshPrabhu, Bushkill, Pennsylvania “