回复：回复：请教关于I-130 filing 的问题

But it seems that this is not reasonable because her son could be automatically eligible for immigration once the I-130 petition for her is approved.

-Not true. You missed understanding of the I-130

Thank you very much. But, according to the I-130 instructions, why one needs to file  only one I-130 for sister or brother and then the sister or brother's spouse and children can immigrate with the sister without filing a separate I-130 for their spouse and children.