A married U.S. citizen and spouse (no special age) or an unmarried U.S. citizen at least 25 years of age may file an orphan petition. The spouse does not need to be a U.S. citizen. However, the spouse must be in the U.S. legally if living in the U.S.
The fastest way is to file Form I-600A, Application for Advance Processing of Orphan Petition, before you identify a foreign born child to adopt. This allows the USCIS to first process the application that relates to your ability to provide a proper home environment and your suitability as a parent. Then, once a child who meets the INA’s definition of orphan is identified, you must file Form I-600, Petition to Classify Orphan as an Immediate Relative, in Behalf of the child.