"家人过得很开心"的英文表达可以是 "My family is having a great time."

来源：这个表达是由 "my family"（我的家庭）和 "is having a great time"（过得很开心）组成的。

英文例句及其中文翻译：

"We spent the day at the beach and my family is having a great time."
（我们在海滩度过了一整天，我的家人过得很开心。）

"We went to the amusement park and my family is having a great time."
（我们去了游乐园，我的家人过得很开心。）

"We had a picnic in the park and my family is having a great time."
（我们在公园里野餐，我的家人过得很开心。）