Just posted on this a few minutes ago in the same forum.
QUOTE
Who May Not File This Form I-130?
8. A grandparent, grandchild, nephew, niece, uncle, aunt, cousin, or in-law.
http://www.uscis.gov/files/form/I-130instr.pdfOnly way is indirectly, Green-card holder naturalizes and becomes a citizen, and they file for the Niece or Nephew by filing for their sibling. Siblings take F-4 priority, which for PI takes 15-20 years to get a visa.
Other option that a member on another board indicated that works is for You to adopt the Niece or Nephew, and then file a petition for a son or daughter.