*Cracks knuckles.*
Boni - Ok he's over 1000 years old and his career is literally 'thief'. He's stolen significant things, like artefacts from gods, treasured possessions of fae, general treasure from demons. He's also done over a thousand years worth of pick pocketing.
Endrit - Just some petty theft from when he was in high school, like cigarettes from convenience stores.
Garrick - Nope.
Maria - She's pick pocketed a few times, but only up to twenty dollars at a time, and she's usually paid it back.
Ohri - She stole food when the going got a little rough.
Oswald - Nope, he's a good boy.
Sark - HOH BOY. Yes, he has. Priceless military equipment, technically he himself is stolen equipment. He's jokingly stolen from his friends but has usually returned it.
Ailbhe - Again, her career is pirate. She's stolen probably a couple of boats around now, a lot of cargo and firearms, jewellery and money and various other valuables. More often than not, it was expensive things rather than sentimental things.
Eli - He was given stolen items? Dunno if that counts, his carer who provided a lot of the possessions he has now stole them.
Vivra - I mean, she's stolen the occasional shiny? Nothing of sentimental value, or of much worth.