The grandparents didn't want to leave.
One reason was because the fishing boat was small; with things and people, it was already heavily laden. Adding two more people could very well result in being unable to bear the weight.
The second reason was that they were old and could not withstand the turmoil. They knew staying meant certain death, yet they chose to remain because they had lived here their entire lives and didn't want to go anywhere else.
For the sake of their two children, the couple bid farewell to their parents with tearful eyes.
But their luck was not good. After they had packed and placed the brother and her onto the boat, someone suddenly appeared behind them and called out.
"Hey, Old Shen ah, what are you doing here in the middle of the night without sleeping?"
Upon closer inspection, "Hey, and Sister-in-Law is here too? Why are you taking the kids out to sea as well? That's not right, not the right time, what are you actually up to?"
