A 17-year-old and her sister, two years younger, have found themselves in a classic sibling feud: the sharing stuff impasse.

As often causes a blowup, one is taking a WAY more casual approach to sharing than the other.

But older sis has incorporated a variable not always on the playing field.

Holding an Open Door Policy for teen siblings' clothing, beauty care products, video games and sports equipment, to name a few, seems to always be the assumption carried by only one of the parties.

When one of those siblings in the trading "agreement" doesn't agree with the terms, friction blooms. And friction usually means confrontation, which in the case of sharing means hiding one's stuff, or securing it away from use in some way.

But a Reddit story submitted to the popular subReddit "Am I The A**hole" (AITA) illustrates that there is another way.

If the variables are right, there is a way to leave the item in plain site, create no change to the status quo and rest assured that a barrier has been assembled, one built firmly on the non-negotiable limits of the overusing sibling.

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The story teller—who deleted her account after receiving Reddit judgment—begins by outlining the source of her younger sister's Achilles Heel.

"I'm 17F, my sister is 15F. She has a mild strawberry allergy. It could never ever cause breathing issues unless she ate an entire punnet, but it can cause hives."

The site of exposure now shared, the narrator moves on to include the category of items shared.

And it jives exactly with that allergy.

"She keeps nicking my bath products, shampoo, body butter/scrub, lotions, etc, which are the only things I really spend my money on. I buy my stuff when I need it and most of the remaining money goes untouched."

"I usually get a floral or fruit scent like rose or pomegranate but I like strawberry and never buy it because of her allergies."

Using this key detail, the defense strategy is implemented.

"I've told her multiple times to stop taking my stuff but she still goes into my room and takes it. So lately, as stuff has been running out I've been replacing it with the exact same thing but the strawberry version."

"Basically everything I own now contains strawberry in some way."

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The narrator does make clear that this is not a revenge plot.

She did take steps to provide warning.

"Everything is clearly labelled but earlier my sister went into my room and, without looking at the label, used some strawberry hand lotion and now her hands itch."

But apparently the itchy hands received all the focus.

The lotion owner found herself on the outs with both her sister and their mother.

"She and mum have both cussed me out saying I can't have this stuff in the house but I maintain that if she didn't go into my room and take my things, this wouldn't be a problem."

The replies to the story overwhelmingly supported the narrator and her methods.

"I'm also allergic to strawberries and if I used someone else's lotion and got hives from that I'd rightfully expect to be called a dumba** for not checking." -- PossumSkull

"If the allergy was more severe maybe, but you have asked your sister multiple times not to use your things and you didn't try to hide the fact that its strawberry."

"You using the products wont hurt her, its only if she uses them herself, which it sounds like you've tried to deal with and she just hasn't listened." -- flaming_paws

"Stand your ground. She'll only have a reaction if she steals your stuff. Sticky fingers can go buy her own stuff." -- LimitedCorri

"Maybe suffering through itchy hands for a while will teach her two lessons -- read labels when you have allergies, and don't steal. That said, you should consider investing in a lock." -- L7ryAGheFF

"You could have unintentionally chosen it. It's her responsibility to ensure she isn't allergic to things, especially if she's taking them without permission." -- SpockVaporizesRock

Some comments, beyond agreeing with her tactics, pointed out underlying issues at play that won't be going away any time soon.

"You should see about getting a trunk with a lock for your room though, not everything comes in strawberry." -- Music_withRocks_In

"What happens when she spends the night with a friend, or goes to college? She needs to learn the world won't work around her allergy." -- CardiacCoder

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And others took note of the parents' relatively minimal involvement in the issue.

"Your parents need to teach little sister some boundaries." -- XperienceIsKnowledge

"I would have a conversation with your mother about respecting other people's property. She should be making sure your sister stops stealing." -- dellaevaine

"I rarely agree with teens, but your mom is in the wrong. She needs to punish your sister for going into your room and taking your stuff without permission OR agree to buy the stuff for you." -- DarcyKnits

Who knew strawberry hand lotion could be used as a weapon?

In most contexts, it is only significant until the shopper's eyes scan one inch further along the shelf and come across cucumber melon.