Communication with parent

[Latercrocodile]

Hi,
I'm step mum to a F12, have been with DP for 10yrs and we have a M7.
My DP and his ex split up over 11yrs ago. She has had quite a few relationships since, had a kid with a guy who is not involved and caused us so many issues including the daughter being on the CP register because of her relationship with him.
Now she is with a guy, has been for about 6yrs, she is secretly pregnant with his kid.....I say secretly as we know but not because they've told us and they won't allow the daughter to tell us.
My issue is communication because there is none! We've tried talking to them about it, recently pushed to have Stepdads number as mum won't give hers, they don't respond to messages I have sent about SD including messages about health and education.
Mum barely parents SD is struggling with some issues and when I asked if she spoke to mum, SD said "no because she probably wouldn't care".
It's a sad situation. I love my SD and always try to do the best and a lot of the time, have to do "mum jobs" because her mum won't but I don't want to be the one that takes over and have her resent me. My DS and her DD have a lovely relationship and see themselves as related as they share a sister but that's where it stops.
How can we try to improve communication when they are at best, hostile towards me and DP.

(Sorry for the rant! 🤣)

[lunar1]

You can't control other people's behaviour, only your own. Sad as it is I would lower your expectations of her, anything else will drive you mad.

How much time does DSD spend with her mum?

[Illpickthatup]

@lunar1

You can't control other people's behaviour, only your own. Sad as it is I would lower your expectations of her, anything else will drive you mad.

How much time does DSD spend with her mum?

This.

I think you just need to accept that the communication will always be minimal. To be honest either your step daughter being 12 there's not much need for you to contact her mum. I'm looking forward to the days we don't need to communicate with my husbands ex to be honest.

It's really none of your business if her mum is pregnant. She's not obligated to tell you.

What is the custody schedule?