[kevincox]

Trying to derive names is basically an impossible problem. I highly recommend the following both as arbitrary text fields:

1. Ask for "Legal Name" if you need it.

2. Ask "what would you like us to call you?"

If you are displaying users' names to others then you have infinite choices but they all boil down to "what would you like us to show in this context". The simplest is just a global name but you could have different display names towards different users/groups.

[dusted]

This. I can only upvote once, so I did, but this. There are about two input fields to take a name: Anything more starts making assumptions, actually, it's an assumption that everyone has one.

Your real name: Your shown name: [leave empty to use your real name]