If I try to add a second user that has an email address the same as an exisiting user(from the same family) I get the "email already exists" message.

Is there any way to allow 2 members to share an email address?

my CB site will be for a sporting club and kids may share their email with their parents (Of course most kids dont these days) but just in case?

In the backend site: global configuration, set "Require Unique Email" to no.

Many thanks, too busy looking at the CB configuration pages

right on.