Thanks, bg_vagabond.
That makes sense. It means, there is no point for me to find out the interview date for my brother-in-law.
The thing is, they both won, my sister and her husband... My sister's interview is scheduled for December 20th, her husband's case number is current in November. So, I was trying to find out about his interview date, hopping that it would be sooner. Obviously, that's not going to happen...
My brother in law was visiting us from April thru October, so first we decided that he would do AOS. I sent DSP-122 back, and got the confirmation letter in June. Then, because his white card was expiring on October 4th, and we didn't want to take any chances, he went back to do CP. So, I resent DSP122, DS-230s back to KCC with a letter explaining the situation. When I asked KCC about his interview date, they told me that they only got his DSP-122, and not DS-230s. I responded including the shipment notice from USPS that the second package with all the forms was delivered to them in September. On top of that, yesterday I got a letter from KCC, and guess what? It was the exact copy of the first confirmation letter from June, only dated October 23, saying "Thank you for informing us of your intention to apply for adjustment of status with the Department of Homeland Security,...".
...Today I sent another letter to KCC.