Sister stole her flatmate’s deposit

You have no obligation to do anything.

It's absolutely nothing to do with you.

Block the girl and her family and if your parents want you to interfere then say no.

This has more holes than a sieve.

I also thought it was only £200 she owed. Even so, You can’t make your sister give it back anyway. She is a grown adult. I think she was stupid to give rent money to another friend but let them all get on with it. Still nothing to do with you.

Honestly, your parents are right. Your sister is being quite foolish here. But your sister doesn't want to know and doesn't care.
So as everyone keeps saying, block the girl on everything. Then if you are really wanting to get involved then speak to your sister and ask her to speak to the ex flatmate and sort it out directly.

It’s a big fuss over £200 for a rich student to make.

Sounds like a dispute over the rightful beneficiary of the remaining deposit and your sister’s view is that she is £800 out of pocket due to her flatmate’s negligence. Her flatmate thinks the list deposit of £2,000 should be borne equally. Ignoring the lying bit, as I’m not sure that’s wholly relevant (she could equally have said ‘flatmate did the damage, so I’m keeping the remaining deposit’ and succeeded in getting it) this is not theft. It is a financial dispute without a clear cut answer. I’d say to flatmate that you have spoken to your sister, you understand there is disagreement over who should have received the money and you have asked her to pay the flatmate half out of good will. That’s all you can do and any further contact will be treated as harassment.

Yiu can't make her give the money back but I'd tell your DSis that a CCJ on her record might get in the way later. If she wants to be a professional then ut helps to have a clean credit record

Block her and do t get involved

It’s nothing to do with you so just block this girl and move on.

She sounds a lowlife anyway with no morals so in a way it’s karma

Ok so rest assured flatmates disagree about deposits all the time, sometimes people do unsavoury things re: deposit disagreements, she's not going to sue your sister for £200 especially if she's in her home country. There is no small claims court of international arbitration – these deal with massive sums of money.

OK, so you block the girl on all forms of communication.

Your sister sends her an email saying, "Look, fuckface, I very nearly lost my deposit because you trashed our flat and I needed that money for my master's. Please see attached all the photo evidence of you treating the place like a pigsty. If you've got any self respect whatsoever you probably don't want me posting these photos on social media or sending them to your parents, friends, boyfriend or employer because no normal person would want everyone to know they live like a pig in shit. You were willing to walk away from your deposit after all the damage you caused because this money is peanuts to you. So fuck the fuck off and don't contact me again. You have no legal case against me here and if you try anything I will counter-sue you for the damage you caused plus my costs of dealing with your mess."

Then block.

I got a message from the girl asking me to help. tell her it's nothing to do with you

So. She has half the money, she took it. How has that got anything to do with you?

God you love to be in the middle of a drama, don’t you? None of this is even vaguely anything to do with you. Block, move on, stop wasting valuable energy on other people’s stuff.

Wrong pity party! I came here at 18 to attend uni, and managed to handle myself perfectly well despite having the English accent in the world that cops the most "acceptable" (no such thing btw) mockery/racism in media and across the world (hint: not a European accent by any means).

I understand there's no point comparing racism but I was a complete foreigner in the UK. The actual foreigner / international student, your sister's flatmate, looks to be handling things by herself too.

It was stressful and painful but I learnt. If my parents helped me, it was through advice and support and then stepping back. Hovering anymore gets a little helicopter parent imo – you do see that on MN sometimes but it's not very healthy.

Also please please don't pretend your sister can't speak English after a 3 year uni degree conducted in English lol. Putting aside the fact that she probably attended school here before that too.

Yes maybe you're being protective, or maybe you just want an excuse to get a little bolshy, but you have to let your 21 year old sister be at some point. When she gets her first job within months, are you (or your parents) going to take things up with her boss and colleague??

I thought you said she’d given all the money to a friend to help with their rent?

I once shared with someone with disgusting habits, and what deposit we got back I took and kept for myself. Seemed fair. Your sister was wrong to lie to landlord (and technically it was a criminal offence too), but not wrong to keep the deposit, bearing in mind where the damage was.

Tell her that if she doesn't stop harassing you you will report her to the police and then block her.

Just ignore them and they will eventually go away. I don't understand why your sister gave away 2400 tho!

Block the girl and don't get involved. Not your problem

It’s nothing to do with you, don’t get involved with the drama. Reply to the messages and block.