Allowing external users access level to be listed as a contact

Description - When creating a request, it would be essential for our marketing department to be able to add user with the external user access level to the primary contact of the request. Currently we are unable to add users that are external users.

Why is this feature important to you - This is important for our marketing department because we work hand in hand with partner/sister cities on marketing needs, workflow and approvals.

How would you like the feature to work - We would like to see the external users access level users populated in the drop down of Primary and Secondary contacts fields.

Current Behaviour - Currently only internal or users with an access level above external users are populating.