When a baby grows up, you can choose for them to travel the world, and if you do, streetpass someone to send the mii to their island, but only for a day, and they stay in a tent. After the day is over, they head to the port and just wait to go to another island. QR codes are a lot more simple. Go to the town hall, choose QR codes, choose one for a mii you want to send to people, and post it on Mii