Sounds like the sisters are being flying monkeys! How long has it been since you disengaged? I did the same thing when my SD was 19 and it has been 10 years. She was into drugs, theft, etc and was in and out of jail (eventually landed herself in prison for 6 months). I had to do it for my mental health and the safety of my two bios. I would ignore it - as you said, they do not know the details of what has happened in the past. 

My SILs are the same with my SD14. They are much younger than DH and love to give him guilt and advice about his relationship with SD and meddle in our lives. 

No advice other than to go no contact. These people will use any info they can to create drama so don't give them any if you value peace.

Trust your hubby to deal with it as he knows his kids and his family. Many times we want to clear up our side or clear our names but there's not a need to do that most times. They just want the drama and when they don't get it they will move on. 

Have you considered blocking telephone numbers from your personal cell IF they text or call you?

people like this want engagement/confrontation, they want to feel like they're "saving" others, like their contribution is so helpful and important, it's a good thing they're here. [Insert eye roll.] If you don't participate, they'll have to give up eventually. It's like playing tennis by yourself - let them run themselves around with nobody hitting the ball back. In the meantime, let hubby deal with it. In general, men seem better about letting things roll off and I think that's what you need to do here. If the sister gets out of line, hubby should shut her down and tell her to mind her own business. She's welcome to have whatever relationship she wants with the skids but she shouldn't be affecting your relationship with them. Sounds like she's assuming all kinds of things - don't humor her.

Share the stories with his sisters then tell them to butt out since they have no clue of the situation or the history.

Behind the scenes manipulators cringe when they lights are thrown on.  My DW had to do this with her own family when their manipulative bullshit got too much for her to ignore or let slide.

She called the on it, things go very tense for a couple of years, then the relationships started to reform with far less of the toxic manipulative back stabbing bullshit.

My skids are not adults, but DH's mother and brother got involved in BM's crazy accusations that we were traumatizing the children. They both told DH that he just didn't love his children enough and he needed to realize that BM was a "good person" and he should "work out his differences" with her. Um, his "differences" are that BM is abusive and a liar and it wouldn't matter if DH did everything she asked (as he did when I met him), she would still treat him like cr$p and call him a terrible person because she has "borderline tendencies" (according to multiple counselors both DH and I have seen separately and together, including counselors who met BM and saw her interactions with DH. 

In response, I've distanced myself from both of them. I'm sure they notice, but I'm not sure they realize why that is. I don't trust either of them and I also know that they both think I'm part of the problem, even though neither one has ever talked to me about it. They have not seen anything that would lead them to believe that what BM says is true, they've just taken her word at face value without asking either DH or I what is going on. Makes me feel like I'm not even part of my own life, in their eyes. 

It's difficult and isolating, especially since we live near DH's family (due to skids) and not mine, but I know we will never get any acknowledgement from either one that what they did was wrong or unfair. DH has asked MIL multiple times for an apology and she refuses, telling him he just has to "move on" and "realize people make mistakes", but she said some really hurtful things and she continues to work with BM against DH (in her mind, she is just supporting skids, but in my mind, she's just keeping the drama alive). I don't have time in my life anymore for people with are that dismissive and abusive, so I'm cordial with both of them, but that's it. 

My younger SILs are the same way and meddlesome with my DH and SD14. They constantly judge him and tell him they don't approve of what he's done with his life and try to make him feel guilty for abandoning SD when in reality BM took off with her and wouldn't let him see her. In their eyes they are like his children and have their own issues with his divorce. The one SIL takes his divorce personally and acts like another SD.  She needs to grow up and take ownership of her own life. She blames my DH and his divorce for her failed relationships!

He talks to them for holidays and only the minimum. It's also a good idea to keep alcohol at a minimum because his sisters get beer muscles.  It's sad to cut off siblings but it's all you can do 

If I get a group text, I'll reply very short and sometimes I won't.  They happen only like quarterly lol but I am not sending gifts anymore, I sent a happy birthday text and that was it. Last gift I sent was very expensive and time consuming and when I asked if we could possibly have a better relationship Bc I'd like to have a better relationship I was met with nothingness not even a "Aw yeah thatd be nice".....: my mantra has been "fuck them kids" for some time now it's working out quite nicely lol.  I would just be cordial if you ever have to see them in person, don't let them drain you anymore.  They lose their power when you just stop caring.  Stop caring about looking like the nice one, the way it appears to other people, any of it.  There's a reason there's a group online for this.  The situation can be very toxic when you have unhealthy ex wives or BMs or unhealthy SKids.  Not your fault!!!!! They don't want to be saved, it's like they want every family to be a wreck just like theirs and you have the right to disengage.  Don't do anything that makes you feel like you're giving anything or can set you up to be disappointed.  It gets better! 

When I disengaged from SD24 Bratty McBratFace SO's family stayed out of things and continue to do so, rightfully so.  Bratty interacts wtih them but if she bad-mouths me (probably does to some degree) they don't let on or pass it back to us.  

If I interact with them I don't say anything negative about Bratty either.  If SO is singing her praises, I just stay quiet.

How annoying for you to have these two grown-arse adults interfering in your life.  Are their lives so perfect?  Where are their kids?  Do they even have any?  I agree with others - just ignore this stuff adn disengage from the in-laws, if needed.