In-laws take our belongings

Queen Mary had had some research carried out into furniture etc owned by the RF / Royal Estate and what had been loaned out by previous monarchs and RF members. Said items then became part of the belongings of the houses they'd been loaned to- Queen Mary tracked them down. Queen Mary would visit, admire, remind the current home owner that said pretty side table had actually been a loan from Queen Alexandra etc and leave with the booty.

Tactic may also occasionally have been employed on items belonging to others that she just liked the look of. However, Queen Klepto reputation a bit of an over statement and is undeserved, imho.

You don’t need to understand the psychology behind this sort of thing, @TheAquaFawn. If you do want to psychoanalyse anything, maybe ask why your response has been to ask about your ILs psychology as if you might be able to find an excuse to avoid some awkward conversations.

what is your DH going to do about the problems his family are causing?

Get your name, sewn or indelibly printed on everything.
Do the nanny-cam thing (x 10?!) some1 else has suggested.
I expect sil has probably never stopped thieving, just your DH hasn’t been told about the later stuff that’s appeared in the wrong house?

My ILs have no need to pinch stuff at all as they're all financially comfortable but maddeningly my FIL and BIL have both stolen things from our house. So bloody annoying, not even a case of claiming things that have been left at their houses, they simply snatched them from our house. Pair of twats. Neither of them have been welcome here for a long time.

Or related to the Lovelock sisters from Thrush Green!

Of course she wasn't! What an outrageous lie!
It just so happened that, on visits to friends and relatives, a positive renark about an attractive rug or nice porcelain figurine would prompt the owners to give it as a gift.
Totally unbidden!

Fawn is the right word here.

"Stop stealing my fecking stuff."

Repeat.

As for Queen Mary; the story I heard was that, when she visited aristocratic homes, she would hint heavily how much she admired certain desirable knickknacks and rely on noblesse oblige to force the hostess to take the hint and kindly "donate " them......tales of aristocratic hosts moving desirable objects out of sight before they could be spotted......

Why are you friends with her?

Really?
You have no advice, a person steals from you and you just keep letting them do it!?
And you refer to this person as a friend!

Really obviously steal something totally absurd from their house, something big and everyday.
Then say, when they ask about it, "See, it's not nice to have stuff nicked, is it?" 👍

OP, you know they are blatant thieves!

If you do decide to let them in your home again, have some strategically placed signs in every room with:

’Watch out, there are some thieving gits about’

They might take offence, which, frankly, they can take as much as they want!

…and corralling them in one room under supervision during their short visit may be helpful.

Jokes aside, I would not entertain the idea of letting them in the house again as they cannot be trusted. They do not respect you.

Wrap up one throw for her birthday the other for Christmas - imagine the look on her face when she opens it!

Was queen Mary a thief?! I don't understand this reference!

I have a friend who does this, it’s really infuriating. Umbrellas, sunglasses, shoes. All small items but items I use regularly and why the f should I pay to replace them because she took them. No advice but I feel for you.

Go to their place with a big backpack, wear a stripy top smile & look them in the eye as you load various objects into the backpack.

Sil wouldn't be allowed in my bloody house

I was expecting it to be, the plate they took leftovers home on, not bloody throws.

They’re thieves. We don’t welcome thieves in our home. Your husband needs to deal with this and not make hamster-based excuses for his sister. It’s like real-life Shameless.

Thieving bastards. They wouldn’t be coming back in my house with behaviour like that.

Bloody hell OP she’s a sociopath. She steals possessions of yours and puts them on display in her home! Absolutely no sense of consequence on her part.

Clearly the matter needs to be handled tactfully as she is suffering from Kleptomania, which may run in the family. Maybe putting up signage in prominent positions (at least 4 in every room) of those fluorescent yellow, 'Thieves will be prosecuted' and 'CCTV in Operation on these premises' signs as a deterrent.

Is it possible to get one of those hand held scanner wands that airport security use (and perhaps a taser gun, in case she is caught taking something)?Obviously, as they are family and you wouldn't want to upset your partner you wouldn't want to go in heavy handed and actually prosecute... but talk to the police to see if they can be cautioned and a dawn raid conducted at their house to retrieve any stolen goods.

It’s absolutely abusive. My youngest sister used to do the same but thank god I have been no contact for a long time now. I remember her and her boyfriend at the time came to my house for my daughter’s birthday and lots of things disappeared. They had just moved into a new flat so presumably need stuff. My bike pannier, quite a big one as I used it for touring, was stuffed full of sheets, towels duvet covers, all the things i looked for over the next while. I really needed the pannier I used it a lot. It was one of a pair. Then I spotted it in my parents house and I said do you mind if i take that back and it became obvious that they knew shed taken it and although I said nothing about that I got a lecture to not accuse my sister of theft. I had just said do you mind if i take that back.

How can someone nick a hamster ?

Apologies, nothing useful to add and not meaning to laugh at your pain OP, but this is hilarious, especially the hamster 😂. Reminds me of the episode of the Aussie lawyer comedy Fisk, where two kleptomaniac clients just blatantly fill their bags with everything in her office that’s not nailed down. S1 E3 if you want a bit of light(fingered) relief!

😂😂 Please op steal one of their shoes each, that would be the ultimate pettiness revenge.