Welcome! If you'd like access to the rest of the forum, can you please post an intro for us? There's a sample sticky at the top to help you out.
As for the co-own questions...I agree with Celeste. I personally wouldn't do a co-own with anyone, UNLESS I had known the person a very long time, knew their breeding practices inside and out, and trusted them with my dogs life. When you do a co-own, it leaves the door wide open for the other party to take the dog for shows, breeding, etc whenever they please. If you do not know this person very well, nor their breeding practices, I would not suggest getting involved in a co-own. If this person happens to be an irresponsible breeder, and does not follow the breeder code of ethics (There is a copy of this listed as a sticky at the top area of the Rescue/Adoptables section), then you will only be contributing and partially responsible for what this person does with this dog down the road.