Can I disable local users when sharing?

Nextcloud version: 11.03
Operating system and version: SLES 12 SP2
Apache or nginx version: Apache: 2.4.23
PHP version: 7.07
Users where added by ldap / AD integration feature.

The issue you are facing:

First of all, thank you very much for providing Nextcloud. We were running owncloud for several years and I just upgraded everything to nextcloud without any problems.
But… users are now complaining in the pilot about the sharing options to other people within the company. Sharing to email addresses outside is no problem, since the user has to type the full email address from that external mail and they just ‘click’ the (email). So everything is fine for that matter.
But if users share something with people within the company, for example… it will display: company user (the ldap local user) and (email).
Can I somehow, disable the displayed local user when sharing? Because it is obvious sending email to this local user does not work and will only work to the displayed …(email)

Thank you!