Right now I have gone in 50/50 with a trusted business partner on some sites. So not to violate Adsense TOS, I used my Adsense publisher ID for the Adsense code on the new sites. My partner of course wants to know how the sites are doing in Adsense, but I'd prefer it if he didn't login to my main Adsense account and see everything. I'd like to give him a login for just his Adsense channels. Is this at all possible?
Why don't you have your business partner sign up for Adsense, and code the site to display his publisher ID 50% of the time and yours the other 50% of the time? That is allowed by the rules and it saves the hassle of having to pass money back and forth.