咱们统称吃饭,但英文早午晚餐也不一样,早/午/晚=breakfast / lunch /dinner (晚餐也可以是supper).
这里我就以晚餐为例了,
Mr Si is having dinner with his family .强调的是他和家人吃饭,不是和别人.
也可以说" The Si family are having dinner now“一般用男主人的姓氏代表一家子,强调这家人在吃饭,不是在干别的.但口语来说的的话应该不是那么计较,都可以的.