>>50136493
If it poses any risk to your sister keeping her kids you should tell her what happened so she doesn't get mad at you if/when she finds out. Then probably sit down with him, tell him you're not going to be angry about what he did and make an agreement to both not speak of this to anyone again. Just focus on mitigating the risk.

What would throwing away the doll change? The damage is done. Put it in a box and get a storage locker if you don't want it in the house, probably still cheaper than buying another doll even if you stay for a while.