FizzTheDrink

I would be happy beyond almost anything

I've been thinking. Since we already know that Sunset is a few years older than Twilight since she was Celestias student before her, so she is probably about 5-8 years older than her. Therefor the human version of Sunset is also older than human Twilight, ergo she probably stumbled upon(pony Sunset) on her human counterpart some time after her arrival to the human world, and maybe explained her situation to her human counterpart. Plus we know that creatures from Equestria age rather slowly in the human world(The sirens)so maybe while Sunset(human) was going to school(probably Crystal high) she let Sunset stay at her home and adapt and learn in the human world, before she can go back home since the portal has most likely closed of another 2 and a half years(that is by logic what 30 moons equates to). We also know she wasn't living alone since someone taught her how to play the guitar, and my money is on human Sunset. So yeah...that's my theory at least.