yep, but when you have posting key, anyone can change that before posting, so its a gentleman's agreement cooperating using the posting key. So, I have always mixed feelings because I wanna use the as much as possible the blockchain features.
As a last resort, beneficiaries could be controlled using multi-sig, but that would be very hard to work with things. So, sharing accounts is actually something that was never really thought about at this level. Usually what happens between everyone is for people to delegate authority and then there is no need to manually share the private posting key.
Anyhow, I happy to give it a try, since with @atexoras.pub until now its working quite well.