I just got my citizenship and going to apply GC for my parents. But my mom is here in USA with me, my dad is still in China. Can I apply for GC for both of them together? I mean just pay once.
-No. You need to file two I-130s, respetively, for your father (for consular processing to get the immigration visa in China), and for your mother (for I-485 filing within US). These are two independent cases, not related to each other. Of course, you need to pay two filing fee.