A Microsoft file hosting and synchronization service.
Hi Paul,
Regarding the display names of the external users which you shared with, they are set by their display name in their organization and will show in your organizations contacts with the same display name. Like the below picture shows in the contacts:
To change the display name which shows in the people picker list, you need to involve the Office 365 admin to change their display name via the following method. Go to Office 365 admin center > Users > Active users, choose the external user which you want to change their display name and click Edit in the Display name part.
After changing their display name, when we choose the people to share our documents, the display name will be updated in the people picker list like below.
However, the display name showed in the “Shared with” part will not be changed. To find the exact people, we need to click on the head picture to get their email account. For your reference:
Regards,
Allan