Thanks Andie - I had like you overlooked the link to start with regarding the two-step verification, but I had managed to get beyond that point and set up the mobile to receive SMS messages, but I was still confused because it appeared to only let you add 'admin'. I've now realized that these are actually 'facilitators' - I wish Apple had made that bit clearer!
Thanks for your clarification on this - It really helped, as i'm now up and running, but I'm sure many others are still confused by this process:)