I have read FAQ and the following quotation: Each business account or personal account on the site should only be used by one individual. This individual should be the owner of the email address used as the login email address for the account.
A Page can have multiple administrators. Each Page administrator will need to have their own business account or personal account. Every admin can manage the Page from their own Facebook account using the "Page Manager" application that will appear in the left hand column of the Applications section once they become an admin for a Page. Every admin has equal access to and the same abilities as the other admins for a Page.
When I have added new admin to business accout it demands the following: Some of the new admin could not be added. You may only add friends or people who like this page. If you need to add a non-friend make sure that they like the page.
I've never done this. The only time I've ever done this with anything is with a firm partnership/corporation agreement since I never hand the keys over to anyone unless we are in business together (or married, etc.).
There are FB horror stories of lost admin control because other "admins" have changed access (and you can't get back in)... True? (in some cases) Worry? Not for me, I don't give people a key to my house, though I let them come in to par-tee from time to time.