A couple of things about sizes.
I wear a street shoe size 13 and a ski boot 29.5, you wouldn't come to that based on all the ski boot size charts.
About 4 years ago when I went boot shopping in the bay area, I didn't find any store that had more than 2 options in a 29.5, most had just a single random boot in that size. All were too narrow for my foot. I found a Tecnica (I believe) that was close.
Your brother in law might be a 30.5, just a guess. And I am guessing the available selection might be slim.
I ended up going to the following shops:
California Ski Company
Sports Basement SF
REI San Carlos
Helm of Sun Valley San Mateo
Any Mountain Redwood City
Demo Sport San Rafael
Found nothing that fit well, came here for some advice and I did a bunch of reading and ended up buying a pair of Dalbellos online from Level 9. I am not condoning buying online, but after all the research I did I was confident they would work, and they did and I never looked back. I did purchase a pair of SuperFeet Carbon inserts.
Looking back I should have made a video documentary about this experience. I went way down the rabbit hole. Now when anyone asks me about buying their first pair of ski boots I give them an information dump.