Alternative of Email attribute

Hi All,

when we add approvers for group membership additions in Active role. it will trigger email to Primary/Secondary owners to that group for approval. Probably when we add Primary/Secondary owners to groups it automatically read their email attribute and trigger emails to them. 

i need to find out a way to add another/additional email address to users profiles (may be in extension attribute or virtual attribute) so when it triggers email on group modifications, it will pick that another email attribute and not default mail attribute of that user. 

I can't make change in primary smtp / mail attribute of users as of now but looking additional attribute for email.

Thanks for any suggestions.