请教8老师

之前问过8老师如下问题，

帮父母申请绿卡期间，他们因为急事回国了，现在绿卡面试下来了，安排在一个月内， 再申请回美证至少要90天，
-Did they have the approved advance parole (AP) to travel? If they did not have the approved AP before they left, their I-485 will be denied. They also have trouble to reenter US due to immigrant intent.

父母回去的时候没有拿到AP,

请教8老师，如果以后想再入境美国还有什么办法吗？ B2签证入境会有很大的麻烦吗？