To lock up all our food etc when we leave

Remove absolutely fucking everything.

Just before (ideally, minutes) they arrive there, post to group WhatsApp etc:

'Oh, since we've had issues with sundries not being replaced, we've decided it's best if everyone takes their own'...

If that message arrives too late for them to pack accordingly... oh dear. What a shame.

While you're at it may aswell leave a massive turd down the bog for good measure

You could always say cheerfully that you are on an economy drive...

I raise you one toilet roll to a toilet roll with three sheets left on it , a tea bag with a little split in it and some out of date milk.

I vote for being petty but strategically. Use a smoke screen of non-pettiness eg a couple of dishwasher tabs, a few remaining teabags in the box. Make it look like the boxes are almost empty of everything but you are leaving them as you are not being petty. This way you are making the point subtly without being obvious that you are making the point. Even leave a pint of milk because thats the nice thing to do and is not expensive. This approach also means you cannot be accused of anything which undermines the SIL argument against you for pettiness before they have even tried - it disarms them.
I would not leave a locked suitcase though - I would take it home with you and store it - because a locked suitcase undermines the subtle approach and could be busted open. I would in future keep your own suitcase of supplies for when you are visiting up there. This approach keeps the peace and shows willing but makes a subtle point - all without meaning you are doormats to your SIL.

You are enabling the situation you can’t change anyone except yourself
you need to set boundaries people-pleasing causes resentment and relationship imbalance

So would I because they would have been done in less time than it took to go to the shop to buy the dishwasher tablets.

How do you know SIL's not playing a game herself, anyway?!

If she’d done it once or twice, I’d just ignore it but if it’s constant, no way. Lock your stuff up. Your DH needs to grow some and explain to the family (pointedly SIL) that you’re sick of arriving and finding essentials gone, so in future, everyone needs to bring their own. (Every family has an awkward one, and they are pains as no one wants to tackle them so they get away with murder!!)

I'd put my stuff in one box and prep a Cheapskate's Welcome Box in another. Swap at end and beginning of trip. Job done!

Ooh..... This!! But maybe the sachets of salt and pepper you get in cafés...🤷🏼‍♀️😁

My level of pettiness has been found 🫣🤣

I think you should be petty but not be obvious. Don’t lock it away, just take it home with you. Then they’ll have nothing and be put out but you can say you didn’t realise things had finished.

You are right, end of !

Nah if sils that’s tight she will have them up for sale in minutes. Free cash.

Oh, please lock your stuff up!
I can’t wait for the update when they arrive and realise. They are CF’s and your DH is too generous with them.

😂😂😂, yep, worn.

The thing is, you feel like you're being taken advantage of, but you've chosen to do all of those things, and you do it knowing full well the favour won't be returned.

Rather than getting frustrated about it and becoming petty, you could just choose to stop.

You don't need to lock up the salt and pepper, but you also don't need to leave a ready supply of loo rolls, milk, bread, dishwasher tabs and cleaning products etc either.

Just stop going the extra mile.

Buy yourself a big plastic box with a lid that you can easily fit in the car and get in the habit of bringing those things back and forth.

It becomes so emotionally charged between family members as unresolved childhood issues can drive behaviour that would never be accepted between non family members! Old jealousies and slights can be played out and family dynamics can quickly become resentments in these situations!
We had a family holiday home that we shared between three siblings (and their children) and parents, whilst it was a real luxury to have access to this several times a year, the arguments and fall outs were frequent!
One sibling always felt they could dictate when they had their holidays, when they arrived and left, they would only do the very basic wipe around of the holiday home, never cleaned, whoever followed them had to do a deep clean, parents would not tackle this sibling as they were the golden child! Myself and the other sibling really tried to follow each other or our parents as it could be seriously grim, the messy sibling couldn’t ever see that they arrived to a spotless holiday home and left it dirty.
The unwritten rule was to replace anything that was broken…the times I arrived and something was strategically placed/propped and I quickly established was broken…TV…Video….wooden blinds…Hoover…shower… I replaced them and did ask the previous sibling if they knew anything, but the reply was it was always working for them!
Most bizarrely was the sibling who would rant each year that everyone else had better weather and it wasn’t fair!

Sadlly, some family members feel entitled and cannot and will not change their behaviour. Sometimes you need to call them out, but I suspect they are teflon coated!

Love this! 😅

Yep, they're CF & very unlikely to change, or contribute to a kitty. Not worth a family rift as no doubt you would somehow end up being painted as the tight one. I think you either just have to suck it up, or quietly decide to do it differently from now on. Assuming it's in the UK, no more fresh milk, eggs, coffee or treats left for their arrival. Stuff not used comes home in a lightweight crate in the boot if it's an amount worth bothering with. Food used up at home, non-perishables left in the boot so it's handy for next time. I'd leave the absolute basics - loo roll if already in the holder, a couple of dishwasher tablets in a container under the sink, a few teabags - but that would be it.

no just leave a toilet roll with one sheet in and a nearly empty jar of condiment. Of course if questioned you simply used stuff up

Definitely take your stuff and stash it. We used to have to do this in a holiday home we owned outright. People take the piss. Half the point of having a holiday home is not having to be loaded upto the eyeballs because you can leave stuff not for cf’s to use it all and not replace it.

or better still, just have a ‘holiday cottage box’ with it all in that you take with you and bring home after. All packed and ready to go for the next trip.

It all sounds so frustrating!

I personally would have a convo and say the current system isn’t working for you and suggest that if it can’t be resolved, you both have a lock box with your own consumables in.

Why not just do the mature and sensible thing if take with you what u need and take it back with u when u leave???