SS stole from my partner years ago. Substantially and regularly. I found this out accidentally but told her and things really blew up. 
 

I guess it's been around 7\8 years since and SS was married. About a year and half ago they split up and SS moved to a rental initially paid for by exSIL. In the last six months SS has had to move - downwards - from a house to a studio flat (he's paying himself)

Since the split he's had £1000's off of my partner and her brother which he claims he will pay back - like h*ll he will!  Deposit for the flat, vehicle rental etc etc. 

i opened her credit card bill and was surprised at how much had been spent on it. She said she hadn't spent a thing on it - so I called the credit card company who took a fraudulent use statement and were going to cancel the card and issue a new one. 
 

She then phoned SS who eventually admitted it, wouldn't discuss it but she called the company and said it had all been a mistake and that was that. Entirely - no consequences for SS and nothing paid back. Now she is going to buy vouchers from him to fund something she wants. 
 

I don't know what to do anymore. About him or his mad sister - she's 43 and he's 38. It's ridiculous. Any ideas?