Can I apply for waiver if my US citizen sibling files for me?
The only qualifying relative who is eligible to demonstrate extreme hardship when applying for a waiver is a U.S. citizen or lawful permanent resident, parent or spouse.
If your petition is based on a sibling petition and you have no other family in the United States, you are not going to be able to demonstrate extreme hardship.
If you have an approved petition from your sibling and you have a U.S. citizen or green card holder parent or spouse, you can apply for a waiver.