I think a chat with a family counsellor or psychologist might help arm you with some strategies to deal with this.

What a horrible situation to be in! Lucky the other kids spend most of their time with mum. All you can really do is keep a close eye on bub while the other kids are around. Let hubby know of your concern do he can keep watch too. Hopefully, as they get older, they’ll get past the jealousy

Would love to hear how things are going for you. Such a difficult situation, I really hope its all going well

Tough! Sounds like the ex wants him back! No wonder he left her with that attitude!

How are things going now.

Keep her in your sight . Talk to your husband about this

I really hope you managed to get things sorted.

I hope things are working out for you. If I was in your position I would keep my LO in my line of sight every minute the other children are around. I think your husband needs to put his foot down with his other children and make it clear that this behaviour is unacceptable!!

I would make sure I had my 5 month old sleeping in the same room as you while your partners kids are over.
I would try hard to interact with them while they were over. Your hubby is the person that needs to put his footdown iI don’t think these kids will listen to you any time soon.

Is there any up date on how things are?

How are things going now any improvement?

I think the idea of family counselling is a good one. Then you can approach it from a united front and they get a chance to get their feelings out too. It could end up being a huge positive in other areas too.

It depends on the childrens ages as to how this is handled to a certain extent, maybe even family counseling would be an option, or less informally you could ask a local community centre if they have someone who can come to the house and “guide” the children into appropriate behaviors if you and your husband cant do this yourselves .. best of luck

I would try getting them to become involved in caring and playing with/for the baby. Once they begin to interact, they should realise what a lovely little person your baby is- if they never get a chance to bond, their mothers influence may prevail.

you need to set some boundaries. most of the time you will find they are crying out for attention. perhaps there was something they could do together. also maybe some one on one time. best of luck