Actually, they have a genuine reason for wanting to come earlier, so I cant really say anything to them. FIL has recently joined a new job as professor, and wont get too many leaves. His current semester ends nov mid, and new semester starts jan mid, so they want to utilise that time, which is understandable.
I am hoping their visa takes time to come, so that they come a bit late. I just want to be able to celebrate our first wedding anniversary just between the two of us, and its on 9 dec. so, i am hoping and praying they come after that.