I posted this thread a week back www.mumsnet.com/Talk/am_i_being_unreasonable/2873017-My-stepson-is-stealing-from-me
One solution was that we put cameras up and we did, we never told dss about them and tried to conceal them as much as possible.
In my room I left my handbag, cctv shoes dss walk into our room, go through my bag, pull out my purse and take £50 out.
So we sent the footage not only to dss Mum but to the police. He was arrested and given a caution by the police.
I'm so glad that I've finally been proven right after being called a liar and being accused of making it up as a conspiracy against dss.
It has caused a lot of grief going to the police for dh from ex but hopefully it is worth it for dss to finally have some discipline.
Thank you mumsnet.