Bio mom put sk in danger

Maybe I’m just here to vent, but if anyone has advice I’d love to hear it. Right now I just know there’s nothing my husband and I can do, as it would be our word against hers but here it goes. Bio mom sees her daughter one day a week for an overnight, and a couple hours on weekday. During the custody battle (and I mean BATTLE, it got so ugly) we found out she has had her license revoked by the state due to multiple DUI’s, so the court order states someone else must drive when sk is in the car. My sk (11) sees her mom drink all day every day of their visits. This is in direct violation of court order but whatever, as long as she’s kind to my sk and not driving her around drunk anymore it’s not worth the fight. My issue is that bio mom’s DD was so hammered he fell and injured himself at dinner the other night. He then drove my sk about 30 minutes back to BM’s home. The court knows the drinking is an issue and we don’t like that she drinks in front of sk but we are trying to pick our battles, as she is very high-conflict. It’s a safety issue and my sk does not feel safe around her mother or her mother’s driver. Her mom has done a lot more and a lot worse to my sk for her to feel that way. She has even said things like “it was a mistake having you” “you’re useless” and things like that. Usually when she’s drunk. My sk is so scarred by this and past issues that we have her in therapy and do our best to provide a safe and stable home for her when she’s with us 6 days a week. I just hate the situation and feel so helpless to do anything. Without direct evidence there’s nothing we can do. BM is extremely talented at twisting situations and manipulating, well everything. We just want to peacefully co-parent but these high-conflict types make it difficult. In the beginning she literally tried everything to chase me away. Even went to the court and got an emergency order of protection not allowing me to see my (now) sk saying I was a dangerous drunk and the like.