We are grateful to the teachers for their dedication and support, which have made it possible for our children to celebrate this special graduation ceremony today.
こんにちは！
ご質問ありがとうございます。
ご質問について、いくつか言い方が考えられますが、例えば、
We are grateful to the teachers for their dedication and support, which have made it possible for our children to celebrate this special graduation ceremony today.
とすると、「先生方のおかげで、無事に卒園式を[迎える](https://eikaiwa.dmm.com/uknow/questions/83743/)ことができました。」となります。
カジュアルに表現するのであれば、
A big thank you to all the teachers for their dedication and support. We truly appreciate everything you've done to help the children celebrate this special day.
としてもOKです！
参考になれば幸いです。
日本 
