Thanks for your comments. Separate I-130 process will take another 2 years as per the backlog. It is impossible to leave him alone as his is a minor (16 years old). Are you suggesting that he should apply for a student visa simultaneously with I-130 from one of the parent after LPR?
Many thanks for your guidance.
Thanks everyone and appreciate your genuine feedback. If we file three I-130s then the sibling can file I-130 now and we (parents) can file when we become eligible as LPR.