Magical resistance due to the stone.

Jen suddenly rapidly blink and got Martin in a strangle hold. Jen whispered to Martin, "Apparently due to the cause of my transformation, I am immune to other magical adjustments that I do not allow. Meaning that unless the stone is used or objects and/or powers created by the stone are used I can not be manipulated."
Jen learned this when Martin tried to manipulate her she also learned that this was only due to her being the official inheritor of the stone. Also as such she could summon the stone if it got into someone elses possession, unless wishes used while the stone was in their possession prevented it. She summoned the stone and said, "I wish everyone but me until I wish otherwise was frozen in time. I also wish I know exactly why I ended up like this and how I can become a guy again."