I need advice

So my step kids mom has a falling out with her family periodically. This current one is the longest one she’s had. She seems to have a lot of conflict in just about any relationship she has with anybody. Including her friends. Just constant drama. We know this not because she tells us but because the children tell us about it because she talks to them about any adult issue like they’re adults. Which to me feels very emotionally manipulative. She spends time with these people, let’s her children build relationships with these people and their children. Then will have a disagreement with them over something minor. Then tells her kids they’re terrible and tells them to refer to them as anything but their damn name. Just very juvenile stuff.

So she has been in a falling out with her parents since right before Covid got bad. So about February. I’ll give it to you from her side of the story since it’s probably the most extreme. She claims her brother is a bad parent and his children told our children that they wanted to run away. She really didn’t elaborate as to why they wanted to or why he’s a bad parent. She says that she showed up to tell him she was taking his kids. Yes, just pulls up to his house and says she’s taking his kids. Well according to the police report and the no trespassing order she showed up drunk and belligerent and screaming, with my step kids in her car. But we haven’t told her we know about the police report because we are in the middle of a custody battle. So we don’t really discuss these things with her just listen. But long story short she’s in no position to take anybody’s kids cause she really isn’t okay enough to have her own living with her. She and her boyfriend have substance abuse problems, lots of DV in front of the children, including her chasing her bf out of their home with a knife in front of the kids.

So here we are, Christmas time. Her parents are on speaking terms with my husband and I. They had their first born in high school and her mother pretty much raised our 12 year old so they could finish school and have actual careers. The kids haven’t been allowed to speak to them. They aren’t even allowed to call her mamaw anymore their mom said they have to refer to her as Kim. Told the kids that they’re terrible people. Told our 12 year old her papaw wanted her to be aborted when he found out she was pregnant. Not that it’s relevant but her parents bought her her first business this year. They aren’t wealthy but they do anything for her. But long story short they want to see them. And they have asked us a couple times if they could bring presents to our house for the kids secretly. And we just wouldn’t mention it to their mom.

My husband is so hesitant because of our current custody battle. We aren’t worried about not getting custody in the end because the kids live a very miserable life with their mom and it’s very sad. But we have to deal with her in the meantime and if she found out she would probably take away the extra time she currently allows us with the kids and just make us stick to court ordered visitation until we are done with court. Which my husband is afraid of.

What would you do? I just think it’s cruel to tell your kids that somebody who has been a huge part of their life is dead to them. All because they didn’t take her side in a silly fight. I feel sad for the kids because they miss her. But i also would feel super guilty going behind their moms back too because we don’t like for there to be lies or secrets we just want open communication when it comes to the kids and I feel like this would be hypocritical of us. Idk what would you do?