I want to cook this recipe for 10-12 people this weekend. If I get 2 or 3 briskets, can I cook them all together in my large stock pot? How migh...

I think it will work out fine, if there is plenty of water as suggested above, and just use the longest suggested cooking time, shouldn't make a difference after 3 hours or so anyway. Such a great way to do corned beef, I love it. But I always make it with World's Best Braised Cabbage instead of steamed.

You'd want to make sure that the simmering water could get to all the brisket -- so if they were stacked tightly, the middle ones might not get cooked as thoroughly as the outer ones. Think you could space them out in the pot, maybe by nestling the onion in between? If so, the cooking time shouldn't change much, but you should double the water.