Thank you for your input. You aren't breaking anything, and you must get that notion out of your mind. Brain tan is actually softened rawhide, much tougher than a chemical tan. Because of this tendency to shrink, if you have used salt or alum on the hide before you brained it, it will give you problems because you won't be able to get it all rinsed out, and it will be working aginst you when you are trying to soften the hide. When you have brained the hide, wring all the moisture out that you can, then continue to stretch it until it's dry, this keeps the natural pores in the skin open, and the hide will be soft and pliable.
Smoking keeps it that way if it gets wet again.
The stretching process can be done by pulling it between a couple of people, or using it for a trampoline like the Eskiom's do, or stretching it on a frame and as it dries work it with a canoe paddle or other rounded object keeping the hide stretched out until it's dry, or by pulling the hide over a rope, anything that will allow you to stretch it, but won't get it dirty or cut holes in it. As it dries, if you feel a spot getting stiff, stretch it out. That's all it takes, but you have to keep it stretched, and it has to be dry when you are done. Oh yes, to answer your question. Yes, you can re-soak in water as many times as you want.