Would mean goodbye to the horse. Bye bye.

Now that it happened once, be expecting more calls to the police if you "step out of line again". I won't live in a house a child controls. 

What has your husband said about this nonsense.

False abuse claims are scary.  I would not want to live in a house with a skid who was involved in making false police reports about me.  What was your husband's reaction to all this?

Horse goes immediately. Sold. 

Your DH is never to leave his daughter alone with you ever again.

install secret nanny cams in communal areas.

and maybe stop policing what kind of underwear a 14 year old is wearing. I understand that you’ve made it a rule in your home but I also would be a concerned BM if some other woman was taking such an interest in my child’s panties.

also, tbh, calling her out for the thong can be construed as you calling her a slut. 

Everything related to her is now your DH's responsibility. I would refuse to ever be alone with her, so if DH isn't home, she can't be there. Her underwear, horse and schooling are no longer things that you should even think about. It's all on DH. He procreated her with BM, he can deal with all of it.

Sell the horse and stop worrying about the underwear. That’s dads job and so is the school business. I agree that sd should not be left alone with you. She could say you physically abused her and have you arrested.

She with DH all the time. DH leaves the house she leaves with him. Or back to BM. Totally disengage from her.  Like she does not exist.  House gone. ASAP 

Don’t worry, I’m guessing she won’t be coming over anymore.  

Where is your DH in all of this? None of this was a stepparent’s job to do. 

My DH never cared that I helped him police the clothing that couldn't be used at home.  To hell with what BM thinks.  I had two young sons at home.  To hell she was going to walk around with camel toe and boobs hanging out around them.  HELLL nah!    Sell the horse-tell if she doesn't like the rules she doesn't have to come over.  If she ever calls the cops again for some BS like this you will personally see to it that her stays are completely stripped of any priviledges.  This is YOUR HOME and you will not have a CHILD control what you can/cannot do and say and how you run your place.  This disengagement squad has points at times-but not on this one. 

Not only would the horse be gone but also cell phone, tv, friends, and anything else I could think of. 

I don't see anything wrong with helping police the clothing. She had it hanging out. That would be my biggest issue. I don't even let SD6 run around with her underwear hanging out. I would be less worried aobut the fact she's wearing that, and more worried about the fact she's parading it around the house. That would be my biggest issue anyways (that being said... I don't think a 14 year old should really OWN a thong, let alone have it hanging around!)

She's not following the rules, the horse is gone, either leased out or sold. But no longer your responsibility since she wasn't helping anyways. 

She doesn't need privleges if she's going to do that s***.

I'd also be documenting this and the false claims and what really happens. That was if she keeps pulling that crap you can show a history of false claims and have the story of what really happened documented and written down.

I don't agree with the thong rule, nor that thongs are trashy.  I've worn thongs since I was about your SD's age & have always found them more comfortable..

Asides from that, I agree with everyone else.  The horse gets sold, pull any and all of your own resources going towards this little brat, and all priviledges get taken away.  Calling the cops on you like that is serious, and shouldn't be taken lightly.  I also think nanny cams in all public areas of the house, and never ever ever be alone with SD again.

If your DH doesn't back you up on this you've got even bigger problems. BM and SD do not get to control what happens within your home.

Two squad cars for a claim of verbal abuse?

And you know what? If I caught her wearing a thong in the 8th grade (cause she is a middle schooler . She isn't even in high school yet) and if it was on display for the world to see we would have the exact same conversation. She also has a hedgehog. If she were not taking care of it and I had to do the brunt of the work, again.. exact same conversation. It wouldn't be considered a verbal disturbance either. 

Is the "no thong" her father's rule.. or one you wanted?   Do you have a horse too?  Who is picking up the slack for her not taking care of her horse?  I would have left the school issue alone.. that was a convo for dad really.

I can see her construing the thong issue negatively.  And.. then when other issues piled on.. she probably felt very put upon so she called mommy to whine.. who escalated the situation to calling police.

It sounds like disengagement is in order.  her underwear.. who cares

Her horse.. you don't care for it.. but point out to her father that stall needs cleaning etc.. and that he needs to sell the horse if his daughter won't care for it.

School issues.. leave it be.

To wear a thong or to not wear a thong? That is the question. If the thong rule is a house rule then stepmom has every right to police it. If DH is present then he should say something but if not then it is up to stepmom to enforce the rule or call DH and have him enforce the rule. If DH is not present, the stepmom can act as the adult in charge people! Think of it as baby sitting. You wouldn’t let a kid you are baby sitting break the rules just because the kids are away. In this case, I would just be overly concerned that they called the police so I still say stay away from sd and BM.

I think SM has right to police clothing if it's a house rule. 

If SD won't take care of horse, sell it. Especially after these events. BM is psycho and SD clearly dramatic. 

I would refuse to be alone with her. 

Still waiting to hear where the father is in all of this. Why does the SM have to enforce all of these rules?

Personally I think policing a teen girls underwear is invasive and a little creepy.  I would have been a bit creeped out if exH and his SO had done that to dd.  I don't think it's SM or DH's job to enforce what undergarments SD is wearing unless they are part of some strict religious cult.  I can only imagine the House Rules posted on the wall: NO THONGS! Maybe the rules should be examined, why is this even a rule and why is it important?  Speaking for myself, thongs are much more comfortable than regular panties that tend to ride up and also leave the panty lines.  

The school thing should only have been discussed between mom and dad. For SM to question sd about it was uncalled for.  The horse issue is also something that DH should have broached and dealt with.  It sounds like OP has been put or put herself in a positon of too much responsibility for everything SD and sd and bm are resenting it.  Give the responsibility back to the parents, it is completely their issue.  

If someone made a false report to the police about me i would NEVER be near them again.  

BM called the police on me because she didn’t take the time to look and see when SS was supposed to be coming back from break. She started an argument, I hung up (on my phone not DH’s) and blocker her so she called the police saying I wouldn’t let her talk to SS. Keep in mind I was at work and the CO says she has to call DH between 5-7. This was like noon.  Just disengage 

underwear - Nacho bizness

School change = nacho bizness

Horse care = your bizness

Nanny cams/dont be alone with the little liar.

I too had a drama SD, and her mother, is Toxic, as in Toxic Troll. They both lie and make things up and create drama Feral Check Forger, she has accused DH of abusing her AND her youger sister, who denies all this. When I saw the direction Toxic Feral was taking, back when she lived with us, and the lies she was telling about me, I disengaged, and went no contact, so the worst she can say is I "yelled at her through the bedroom door" during 1 argument.

You must protect yourself, and cover your own self, because DH cannot/will not.

they ride up your arse and certainly are not more comfortable than normal underwear. At home to have a teen dressed provocatively this way is like she’s competing for daddys attention and affection so stepmum is tossed to the side... no one should need to see skids tits are thongs sticking out at home.... you can dress respectfully. What happens if family come over, is sd walking  around with her thong hanging out? She clearly is wearing too low cut pants if her underwear is hanging out

having cops called on me based on a lie, i’d be out the door. Because my spouse/partner has put me in an unsafe dangerous situation all because he couldn’t parent and control his kids. Thats never ok!! Op needs to nanycam the shit out of her house now and be on her watchful guard, diary everything times dates activities she and sd are doing incase another false allegation like this comes out...