Gift Cards and Small Children

This family of three came in; a mother and two kids under the age of ten. The mom had her hair in a nice bun, but she was wearing a man's overcoat, camofloage sweatpants, and leapord-print slippers. Her boy was wearing a grey thermal and grey p.j pants with skulls and cross-bones. The girl was wearing purple sweatpants and an oversized floral print long-sleeved shirt.
I noticed them when they came in because the boy was yelling and the mom was trying to gain control over the girl, who was also screaming. When they were being rung up by my coworker, I was watching the girl paw through the gift card section. The mom was getting into an argument about the price of toys and the state is disarray our toy aisle is in. I was just about to say something to the little girl, but I had my own customers to ring up, and I realized she wasn't pulling anything else off the shelf.
As they were leaving, I noticed both the kids had a handful of gift cards in their hands. As they walked past my register I said "Whoa, whoa! Did you wanna pay for those cards?"
Mom said, in a snotty voice, "They have no monetary value."
"Yes, I know that. But they are still our cards and I cannot allow you to walk out of the store with merchandise." With a neck roll I said, "You need to put those back right now."
"Other stores let us take them."
"Yeah, o.k"
She apolgized to her children for not being able to take them, then handed me the bunch the girl had. Her boy angerily tossed them at me and it took a whole lotta willpower not to snap at him.
"Should we put them back?"
With a serious attitude I said "No, I'll do it."
As they were leaving the little girl grabs a box of cookies and hides it behind her back.
"Hey! You need to put those back right now!" You little bitch.
She giggles and runs to her ma who says
"She would have brought them back."
I said "Yeah, right. No she wouldn't."

The reason why this was so irritating is because putting up gift cards is very aggravating. And it was a weird thing to steal, and it probably means she's got some scam that her kids are involved in. And I hate disrespectful children. If I see them in my store again, we will have problems.