I don’t want to condone lying, but maybe her glucose level drops and she needs the candy.  No matter what the consequences may be.  Ask her how she is feeling when she wants the candy so bad that she is willing to lie to her parents and/or  steal it.  

My (9y/o SWCAH) child has trouble with low blood sugar.  Sometimes it gets so bad he gets very irritable and hunts in the kitchen for something to raise his sugar level.

Just wanted to give another perspective to the lying and stealing.  Good Luck.