The author and her sister to keep their undocumented immigrant status a secret from their friends because they were Concern about their friend's judgement
According to Chapter 2 of the available search results, the author and her sister keep their undocumented immigrant status a secret from their friends because of fear of their friend's judgement.
The passage states that the author and her sister are afraid that their friends might find out their secret and judge them for it.
They prefer to keep it a secret to avoid the potential judgment and scrutiny from those around them.
They were afraid that their friends would not understand their situation and would judge them negatively.
This is a common concern among undocumented immigrants, who often face discrimination and stigma due to their status