Remove it. Report the piercing shop for allowing a minor to be pierced without parental permission. An aunt is not legally allowed to give consent.
You tell your sister she is no longer allowed to be with your daughter unsupervised. I don't think you're making too big of a deal. You're not beating her up, you're not filing charges against her.
You're giving her a consequence to her irresponsible action. Who knows what kind of shop she went to if she doesn't make mature choices, and they didn't require parental consent (which would be a huge state code violation) and who knows what your daughter was exposed to there. The least of which would be a mild infection, the worst could be a lifelong one due to a dirty needle.
If a shop doesn't care about consent code violations, they're not going to care about health codes either.
Make your child take the piercing out then find out what parlor she was taken to and report them for not only piercing a minor, but doing so with out parental consent and keep her away from your sister. And see if you can report your sister for having your child pierced behind your back, pretty sure you can.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.