I am U.S citizen.I am applying green card for my dad. all of his children ( my brothers & sister ) are above 21 y old & I have not applied green card for my brothers & sister YET. what should I answer to that question?
Your brothers and sister are not considered your to be your father's "child" for purposes of this particular questions because they are all over 21. You do not have to include them in your father's petition and will have to file separate petitions for them when they decide to apply for their green cards.
The sons and daughters of your father are not able to " follow to join" your parent according to the fact pattern that you have posted. Hence, the response should be "no".
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