I extend a warm welcome to you on the behalf of my colleagues.

我代表同事向你表示热情的欢迎。

And I would speak on the behalf of our team, it was really, really tough.

我会代表我们的团队发言，这真的非常非常艰难。

She spent more than a decade persevering and advocating on the behalf of those whose stories are marginalized, or not told at all.

她花了十多年时间，来为那些被边缘化或根本得不到关注的人提供支持和帮助。

To speak on the behalf of our group is an honor that I am not sure if I am qualified for.

代表我们组发言是一种荣幸，我不确定自己是否有资格。