A lot of the parents were brought to tears when they saw their kids singing their farewell song at their graduation ceremony.
この場合、次のような言い方ができますよ。
ーA lot of the parents were brought to tears when they saw their kids singing their farewell song at their graduation ceremony.
「多くの保護者は、卒業式で子供たちが別れの歌を歌っているのを見て涙した」
卒業式で歌う歌はよく farewell song と言います。
to bring to tears で「涙する・目に涙を浮かべる」
ご参考まで!