How do you use two SalesForce fields in the "From Name" field?

I'm trying to use a first/last name in this particular email, but there's no "multiple fields" button and nothing I can find online.

So if I wanted to put two fields, how would it work? I can't imagine I can only use one field because what if you wanted to use a first and a last name.

Would any of these work? Or am I stuck having to choose JUST the first -or- last name?

{{company.Account Owner First Name:default=Default Name}}

{{company.Account Owner First Name and Account Owner Last Name:default=Default Name}}

{{company.Account Owner First Name & Account Owner Last Name:default=Default Name}}