From this passage, it becomes clear what I previously mentioned; specifically, that Joseph had just two sons up to that point: Ephraim and Manasseh. Given that many years had passed since the family's move to Egypt and as Jacob approached his death, Joseph could only bless these two sons. At that moment, his children were still very young, dependent on their mother for nourishment, indicating that they were not yet able to have children of their own. Therefore, when Joseph's father and brothers arrived in Egypt, he could not have had grandchildren through his sons.