I have no idea how is best to move forward. We've had a long journey and tied the knot this year, with a 3 year old ours baby. All our children attended and enjoyed, participated in the wedding etc. following the wedding teen SD alienated child behaviour seemed to ramp up again. Visits became less and less. Then in the summer took a complete u turn and stop coming all together. 
 

waited it out/gave her space, she was pushing asking for cash to spend with her friends but refusing to participate in any family time at all with us. 

Got to September and asked her to come on a last minute holiday with me, OH and my bio teen. Her mum refused. Eventually gave up after ALOT of fuss. She joined us on holiday. All was great until my teen saw messages between SD and her mum really bad mouthing us all. Radical stuff. Bout how evil we are. And how ugly we are to be around why would she even like us. Her dad is pathetic etc etc and she's basically saying... don't think I'm up their arse just cause I want a holiday off them. And how she'd rather have an expensive coat that spend time with us. We sat he down, explained how sad that is to see and asked her does she want to spend time with us. She sat silent. Her dad was in tears, really hard watch. Then I said she should be visiting on her court ordered time at the minimum every other weekend, or an arranged alternative if something important is on. She said ok. 
 

first weekend back was her dads big birthday. We booked and paid for all plans long weekend etc. she decided she was too sick to come. She also did the same Father's Day. My teen is like... what's going on are you really not bothering etc she flips it and says she's not coming anymore. Messaged my husband he's "lost her as a daughter" and gone on strike again.

Now he previously responds to manipulation. Not so much now but I can see his grief. We have other children whom still caring for and love to come. Age 6 and 10. Of course they are beigg by alienated too and their mother scares them. Court are not interested we've established this.

So are we doing right by continuing our family as we do, making memories celebrating together etc and just leaving the door open to his eldest? I feel like I can see she's headed this way a long time but OH struggling to process and know how to handle. 
 
He told me his teen said I don't like her (her and mum make me scapegoat of course). It's my own daughters birthday too soon and we celebrated the whole of the families together with a meal etc even hers now I know she will reject my daughter and not bother. So I say that is behaviour I don't like. I can't pretend to allow her to act hurtful to the younger children just because. So I guess my question is, is it even possible for me to disengage from one step child? Shes really something else for spoiled brat attitude right now. The whole house engage is shared responsibility/chores and she stood arguing with me telling me she will rinse her own cup and not a single cup more. It's really ugly to see. 
 

thanks