Thanks for an A2A anonymous, As a sports person myself I do check few websites here and then for any sports events near me. But as you specifically mentioned that you needed an app or website which will tell details of events near your locality for your child and should be affiliated to a respectable association.
So, I did quite a research on this(you could thank me later) and find few websites
1) Book my show: You definitely must be aware of this site, it provides a good details of events and “sometimes” recognizable sports associations too. But it's always a chance of sometimes on this site. At the end of the day, there is not a variety on this site regarding sports events which I assume you are searching out but who knows, you could always try your luck on here.
2) Play Your sport: Well that was fun till it lasted but this site does not stand by it's name, honestly. There was no variety(again) and they were just trying to sell products and merchandise of their brand.
3) YoGems (https://play.google.com/store/apps/details?id=com.yogems.userapp.main&referrer=utm_source%3Dother-websites%26utm_medium%3Dwebsites%26utm_campaign%3Dqueryhome/): This app was a real gem hidden in the coal mine, ngl. This app stands for whatever your requirements are from a sports app are. This app provides its user with schedule, results and stats from all school to state level events held in India by school boards like CBSE, ICSE, SGFI. Making it, the only app based in India which provides info about these tournaments. All tournaments listed on this app are affiliated from reputated organizations and are organized by brands like Decathlon, which is a heads up for any participants. You could even register in events near you from this app and it also handles age verification documentation very swiftly.
All in all, I found this YoGems app most useful, productivity wise and by also considering that your kid is still in school. So by participating in events posted by YoGems of CBSE and other school boards, your kid could definitely gain some huge experience and learn from that. But at the end of the day, its totally your choice what website or app you find most resourceful. Some of the other notable websites are
So best of luck to you and your child in finding a perfect sports event