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.
-Your step-son is considered as your immediate relative (treated as your biological son), the same status as your wife, so you need to file a separate I-130 for him. This is different from non-immediate relatvies of US citizen, e.g. brothers/sisters of a US citizen, etc.