I am a US citizen living in Maryland. My parents got their Greencards through me. They are going back and forth between US and Germany since they have 2 children living in the US and 2 children living in Germany. My parents don’t work in the USA. My younger siblings who live in Germany are German citizens. I would like to apply for their Greencard as well. They are 22 and 26 years old (unmarried). I understand that my parents would need to file Form I-130 to petition for the Greencard. My question is should my parents petition for their children or should I do it for my siblings since I’m financially better off than my parents. How long would the process take if they petition or if I do it? How much would I be looking at paying?