The bad news is that when I tried to turn on the section in the basement to get to the carriage house, water came out in unexpected places. So I'm not 100% sure I understand what's happening there.
Debugging sucks in any medium.
Also, one of the shutoffs I just installed has a leak -- when I opened it, it dripped on the downstream side. So I have to replace it, meaning I have to go to the store first because I've already installed all four of my shutoffs. And after I do that, I have to figure out why water is coming out of the hot water pipes even though when I cut the line to the hot water heater to cap it, it wasn't wet. That, I don't get.
At least I have lots of cutoff valves, though! Most of which don't leak.