Your parents can enter US first and then, you file I-130 and they file I-485 together. They also can choose to apply for the immigration visa in China after your I-130 approval. But your brother and sister may have to apply for the imiigration visa in China because their Priority date needs about ten years to be current and it is nearly impossible for them to keep a valid status in US for such a long time to wait for the PD to be current to file I-485 within US.