So apparently there are 3 slots.

If you look carefully, the upper left slot is called "Names". And the others are called "Name"

This means on the upper left corner is for two Characters. Just like me and Adrien on the Bottom right.

The other 2 slots are for 1 character

Something like this:

Upper Left slot: Drei & Axel (2 characters)

Upper Right spot: Jade (Singular character)

Lower Left spot: Marcus (Singular Character)

Lower Right spot: Aaron & Adrien (2 Characters)