I've never tried to register that many people at once, so I ask this purely out of curiosity. Would having to enter information for 6 people end up risking the race(s) selling out by the time you get to check out? Would it be better to split it up based on how many people/devices you have? Two groups of 3? Three groups of 2? I know any option leaves room for races selling out, but I was just wondering...
I still think I'd want to register everyone together. Assuming they won't have POT, That leaves masses of people who will get more random assignments to corals. If you register together then they should have you all in the same corral. If not everyone could end up split up. Now everyone can just drop back to the latest corral on race day but that might not be ideal.
Considering both of the above, maybe we will split up the 5K and 10K people. One of the 5K's is a 9 year old so we don't want him in a different corral for sure.