There is a former addict in my family with whom I have no trust in. They are overall sober but still have anger/hatred towards others. They have shared and continue to share with me all their negative opinions on things, people, and they way things work around them. I've also heard conninving comments about plans to sabbotage people though I'm not sure they've ever been followed through on. I just don't trust this person but even though they are a part of my family, I have fun with them overall minus their bad attitude. How would you deal with this?
Example: I left them borrow something of mine for 24 hours and it comes back in worse shape than it was in. When I questioned it, they got all defensive and accused me of blaming them for the damage.
Re: how to trust a conniving sibling?
I second PP, though who knows if just distancing yourself will be enough to turn them on you. Basically, you can't trust a conniving person, sibling or not. Stop trusting this person with your belongings, and I'd be spending less time with them.
Good luck.

"You know you're in love when you don't want to fall asleep because reality is finally better than your dreams." - Dr. SeussUhmmm that sounds a bit psycho.
Uhmmm that sounds a bit psycho.
It must suck to find out that a person's terrible behavior is still terrible when they are sober. (If that sounds snarky, I don't mean it to be. I imagine you previously thought wow, those drugs/alcohol are really taking their toll.) But you aren't required to stand by them just because they have managed to get sober.
This sibling sounds unhinged. I agree that you should distance yourself.
See, this is the thing about "family". People are people are people. Screwed up, untrustworthy people don't exist in a vacuum w/ no family. They have families - clearly.
The point being- just because this person is "family", I'm not sure why you feel you "have" to trust them. You don't. You know the kind of person this sibling is. Work with that. Not w/ what you WISHED your family was like.
~Benjamin Franklin
DS dx with celiac disease 5/28/10
LOL! I love this!
It's like you excused your brother for being a complete d*ck because of the drugs/ alcohol but now that they're sober they're still a d*ck. LOL!
So don't let him borrow your stuff. Don't be his confidant and just be normal and civil around him. Your title says How to trust a conniving sibling? The answer - you don't. What's the point?
Chronically hilarious - you'll split your stitches!
I wrote a book! Bucket list CHECK!
http://notesfortheirtherapist.blogspot.co.uk
I have almost the same problem. I'm right there with you OP. Hopefully my story could give you some help.
My sister who is a year younger than me is gay. Not that there is anything wrong with that. That is her life choice and I respect that. Around the time of our wedding my sister started causing a lot of family drama. She was originally invited to the wedding, but after much thought my husband and I had to ask her not to attend. We didn't want her to cause problems with the family on our wedding day.
After the wedding we decided to wait to establish a relationship with her again. After a few months we figured out that she lives right across the street. Knowing that, we decided to try the relationship again. But it didn't turned out like we had hoped. My sister used us. She still lives across the street, but we don't talk to her anymore.
I understand that you do want a relationship with this person. I would suggest stepping back for a little while and come back to see if they have changed later. I hope everything works out.
I'm not sure how your sister's sexual orientation is relevant to your anecdote? Was this unbearable drama caused by her evil gay-ness? Whew. Thank god you got that dealt with, wouldn't want a gay sister at your wedding, right?
Seriously. Not to post-jack but that was about the strangest random homophobic insertion into a story I've ever heard. I had to read it twice, 'cause I was like wait whosawhatnow?
Chronically hilarious - you'll split your stitches!
I wrote a book! Bucket list CHECK!
http://notesfortheirtherapist.blogspot.co.uk
Ummmmm yeeeaaahhh......having a gay sibling is totally not like having a sibling who is an addict....yikes. I'm hoping against hope that that is not what you meant.
Yes, this exactly.
REALLY!!!!! I feel sorry for your sister.