Personally even if my sister didn't believe me, it is MY snake and MY rules. I wouldn't/don't care if she didn't believe what I said if I say no, I say no and that is IT! No ifs, ands or buts! And if I found out she went behind my back ((Even if no harm was done)) I would be PISSED, even more so if something happened to my snake. Not only did she probably needlessly kill an animal she did so behind my back. You would do well to set her straight and tell her there is no way a lizard is getting into your tank.