MDL-31776 added Additional name fields, with the use of the fullnamedisplay setting to define which name fields are used across the site.

Unfortunately, it doesn't appear to accommodate users choosing to use different name fields. E.g. Some users specify an Alternate name, as well as their first name and last name - but some don't.

Perhaps fullnamedisplay could allow multiple definitions, separated by a token, e.g. "alternatename -> firstname middlename lastname -> firstname lastname".

When displaying a user name, fullnamedisplay would be exploded on the token to retrieve the definitions, and the name is then formatted using the first definition where all it's placeholders are present in the user name object.