Go right ahead and do it, and she doesn't necessarily have to be a Minor Element. How you want to fit her in is completely up to you.
I'd run anywhere else but here. Yeah, I'd light the match to burn all my fears, and now you and I, we don't differ. You gotta learn that an ending don't mean it's over.
The character you're thinking of making running an occult shop could work, and off the top of my head, there's at least one other type of human known as a Psion that can initially be what the Elements may possibly be mistaken for, especially Avalon. Though it's confirmed that you're more likely to be chosen to host an Element if you're a Psion, and while they can be mistaken for Prophets, the latter is exclusively for predicting the future through various methods with only one in a thousand (five in five thousand total Prophets) per generation having retrocognition.
Statistically, only around three thousand people per generation can turn out to be Psions, and it makes someone having any sort of powers stand out once they manifest, especially if it turns out they're one of the Elements.
I'd run anywhere else but here. Yeah, I'd light the match to burn all my fears, and now you and I, we don't differ. You gotta learn that an ending don't mean it's over.