Remember folks, your Miis will only go to other people's consoles if you set an individual Mii to "mingle" in the edit character mode.
So you both have to swap codes, and enter them, plus you have to set individual Mii's to mingle if you want them to actually travel to other people's systems, where they will show up in that other person's Mii parade.
Then if that other person wants to actually bring your Mii into their system for real, they have to move them from the Mii parade, into their actual system Mii plaza.