I don't see any way of keeping your baby a secret from the BM forever....so it sounds like it's just a matter of timing as to when she'll go off the deep end. Either she'll do it now, when you tell skids, or she'll do it later when she finds out about the baby from some other means. 

If I were in that position, I'd probably tell the skids, get it out of the way, and be ready for the crazy that BM will bring. That way, you are prepared, and skids can't say you tried to keep them from sibling. 

I would just tell them. They're going to find out eventually. Just tell them. BM is going to be crazy regardless of timing. Once you tell Skids. The ball us in their court whether they come around and want a relationship with their new sibling. 

If you feel that telling the kids could put your life, your babys life and your DH's life at risk, then no I would not say anything.

I have a PASed stepdaughter who is an adult. My uncle just passed recently and neither DH nor myself went out of our way to try and find her and inform her. Part of cutting people out of your life means you are no longer privee to things going on in their lives.

Communication is a two way street. I understand they are kids, but they are kids who will pass the information along because they have been brainwashed too, cut off the communication and it gives them nothing to provide the crazy BM with.

Your family has a restraining order against the BM?  That's kind of scary, and I wouldn't want her knowing anything about me.

How close (geographically) are you to BM?  What is the likelihood of her finding out if you don't tell the kids?  If it's likely, I'd tell them.  If not, I would not.  If at some point they come around and get past the PAS, you can explain why you chose not to tell them.  Your physical safety trumps the (currently non-existent) relationship, IMO.

Plus, drama-free enjoyment of having your child!

It seems that the relationship is a no-go anyway. I would tell skids later, after all the important giving birth. Keep your family safe from high conflict BM = number 1 priority.

I think the safety issue is real, but seems like if you don’t tell them it will always weigh on your mind. 

While SS was alienated, my father died, and DH did tell him. No response, but there was an anonymous donation that I always wondered about (BM would have done that if SS wanted her to, believe it or not).

Our position on alienation was never that he didn’t deserve to know about our lives. 

Send a e-mail ?  You do not talk to them?  No way to slip it in.  I would not worried about, when they find out, they find out.  It no good way at this point how to tell them .  They are just going to told they are being replace with new kid 

Normally I would say you should tell the skids, but if safety is a concern you need to prioritize your child’s wellbeing over the feelings of the PAS’d kids with the crazy BM. 

His family are advising you not to say anything, I’d listen to that. There’s good reason for it, and personally, I would never put my kid in danger just to avoid hurting the feelings of my DH’s previous kids, alienated or not. 

Will they find out about the new baby? Yes, I’m sure eventually they will, and it will hurt them, but I still think your & your baby’s safety needs to be the priority. 

Does BM know where you live? Work? Can you change those things? If you don’t have them already, set up cameras everywhere around your house. If she’s already violated restraining orders I wouldn’t put it past her to try something if/when she finds out you have a child together. 

This normally wouldn’t be my advice, but your safety needs to come before the kids feelings. It’s a terrible situation to be in. It sounds like you’ve got your family’s support which, which is a definite plus.

and the kids didn't know yet, the kids came to their father and said they thought someone had died and that BM just hadn't told them yet the way she was acting.  She cried and carried on for weeks.  My stepkids waffed in their feelings and were present for the birth of their sister in the hospital room with me and they were fighting and bickering and it ruined my birth experience.  Just fyi.  If it were me, I would send them a birth annoucement after the baby is born.  This is your first child and you don't need any stress and drama.   

I wouldn't say anything.

I understand where you're coming from that this would be the final straw in the PAS game, but it will be the final straw either way. If BM finds out she'll say, "Your father is keeping your beloved sibling from you." If you do tell BM, it will most likely be, "See how little your father cares? He's already setting up a 'new' family without you guys." There is just no upside.

If, at some point in the future, the kids manage to outgrow the PAS and try to reconnect, this might be a sore spot for them, but if they've gotten to the point where they see the truth, they will understand why their father didn't tell them.