To have more than one character you go to create when you get to the character page and then make your new character. It doesn't delete your old ones. You click the arrows to switch between characaters. You can have many many many many characters at one time

Adoption Centers: People make their name "Adoption Center" and usually hang out in bonfire island. In character creator you can make your character super small. These are what most people do then they name them selves. Ex.) Kiara Cub or Annie Pup
They then go to the "Adoptiong Center" wolf or lion and hang around. Other wolves or lions pretend to have "mates". They go to the adoption center and pretend to adopt a pup or cub. The "adopted" animal then follows the other wolves or lions around pretending that they are their parents.
No actual mating, producing of offspring, or anything of that sort actually happens. It's all just pretend.