Should possible to put group members with emails address instead of name and surname

Customer has primary (PAB) and secondary address book (SAB) managed by Directory Assistance. When someone has the right to edit SAB to create a group and put members into the group (he/she can put members from their private, PAB or SAB or type members manually), the name of the members are just First name and surname. When co-worker select the group, he/she gets an error delivery for all receipients that were added to the group from creators private address book. Is it possible to put group members with emails address instead of name and surname?. They can manually add the email address and it works. But, it is not possible for an end user to put the email address manually in the groups.