Yeah the fact her grandma got in trouble for the kid locking her outside is.... Like there's no way to safely bring someone who you can't even punish for something so bad.
Her parents are setting her up for a very difficult life, particularly BC learning boundaries, rules and how to co operate with folks is vital to functioning as a teen let alone an adult.
Hopefully her older siblings and Oop's parents have at least had some good habits rub off onto her.