To issue ultimatum to DH about his ex?

YANBU at all. This would drive me insane. Poor children!

No not in the first post. Op says it in the 2nd post.

This is shockingly selfish behaviour by her. Never mind how understandably irritating it is for you, it’s a terrible way to treat her own young children. These children didn’t ask to live in two households and they need BOTH their parents to commit to providing stability. Neither are currently doing that. She will be impacting her own children’s long term mental health.

Agree with @SquatWeightaMinute

Ask him how he thinks this would work if you were to separate. I don't think it's unreasonable to consider ending your relation in these circumstances. You are have both your and your DC life dictated by someone else, all because your DP refuses to do the right thing for anyone other than his ex.

She will not stop contact and even if she did, she wouldn't have a leg to stand on in court because the status quo has been 50/50.

She sends her rotas when she receives them or you go back to set days.

Not unreasonable - though I have to say I initially misread your post and thought he had 17 children with his ex, no a 10yo and 7yo at which point I would have advised to run for the hills.

I think it is totally fair to insist that there is an official and binding agreement - ie a schedule planned monthly in advance as soon as ex’s shift rota is released. You DH needs to understand he has made a commitment to you and your DC so he needs to step up and balance the needs of both families.

No wonder her family jumped ship - she sounds like a
total nightmare! I would actually just send them both a simple text stating that you have had enough facilitating their dysfunctional breakup and they need to get their shit together for the sake of their kids. You are going to focus only on the care, feeding, collection, education and entertainment of your own kid and their kids are now none of your business.

Can he have them full time, she pays CMS so they can go into wrap around care as needed and she can have them EOW/one night a week as her shift allows? Poor kids no one cares about them.

OP I think the best way for you to address this is to focus on the impacts on the children (all 3 of them). They need consistency and to know where they are going to be at any given time and this will only get more important as they get older, go to clubs/play dates etc. it's not fair to them as you've said and focusing on this slightly gets away from you having to point out how wrong she is.

Yanbu, obviously. No ultimatum needed-that’s a bit OTT-but definitely he needs to put his foot down. My Dh has his shifts a year in advance, no idea about the NHS, but presumably it’s a fair way ahead to allow for management of wards etc. she needs to stop assuming he’ll just have the dc last minute. It’s bonkers, you can’t arrange anything!

OP have you pointed out to him she can’t stop him seeing the dcs as paid for childcare for shifts is near impossible (without hiring a full time live in nanny).

she needs him to have the dcs regularly, and not on set days.

so he goes back, he needs at least a weeks notice of her shifts or he goes to court for set days and she’ll just have to sort childcare for her shifts that fall on her days. If shifts are short notice because she’s been asked to do overtime, she calls him first before agreeing.

I imagine he would, again, move on very quickly and find another woman to pick up the slack.

Sincere apologies, it was her second post. Which says “I also work in the NHS”.

But Irrespective of any of this, the situation needs to change!

She’s hardly likely to stop him seeing the DC as she needs his help to work her shifts. So unless she changes her job she needs you or will have to sort childcare. Your DH needs to have a formal conversation with her stating he needs the rota xx time in advance. he can explain its unfair to their kids to be put in this position.

An excellent point. The OP’s DH should have this pointed out to him.

@AnneLovesGilbert it does not state that OP works in nhs in the first post! the ex works in nhs. the OP does shift work but it does not say where. we also do not know if dp works shifts, which would be useful to know.

This situation is untenable, your DH needs to toughen up and say he wants the rota or you go back to set days and her shifts are her problem.

If you left him and chose to be as awkward as her over child arrangements he would be in a pickle wouldn’t he. Three children randomly turning up needing to be looked after, he would never cope.

YANBU
This would drive me insane OP.
Issue your ultimatum and follow through.
What are you? Chief cook, bottle washer and free child minder?
Neither your DH or his Ex could get away with any of this is you weren't around.

There is zero risk of her refusing contact - she should be sending you bunches of flowers and DH should be treating you for your help!

You are being used OP. 😔

I agree she won’t stop him having them, she needs the help to work. He wants an easy life so is choosing to piss you off while appeasing her. Time to make him more worried about upsetting you. If you’ll carry it through then do an ultimatum

I totally get your frustration OP, having witnessed a ‘terrified to rock the boat’ dynamic with my DH and his ex. Do you really want to end your marriage though? I would be more tempted to move out for a while, telling DH you will return when it’s sorted? I realise finances may not stretch to running two households though.

For the sake of your child, I wouldn’t be issuing ultimatums or threats at this point. Doesn’t mean you can’t put boundaries down- like saying you can’t continue to collect or change plans at the last minute. But I would phrase it as in the interests of your child, which it is. Explain how much it is affecting you and making you unhappy which is impacting on you all as a family. Going in with anger and frustration will only get his back up, and make things worse and make him feel like you’re both against him. What do you really want out of this? To break up the family or make the situation better for the kids? You need to be smart about it because everyone in the situation is tired, frustrated and resentful

Why do people post these questions without reading even the opening post?

It’s in the first post that OP works in the NHS.

I would put my foot down with your partner, when you get a call saying to pick them up from school, just “sorry I have plans made “ need to produce a meal out the hat “sorry you will have to send out, what I’ve planned doesn’t stretch” need to sleep over night “ sorry haven’t made beds yet, you know where stuff is “ and stick to it until he sees how it effects you and how much you stopping will effect him, he’ll soon do something about it then.

Who actually takes care of the step kids? You or DH?
Does he work? Are you a SAHP?

They have them 50/50. Why is he talking about her stopping contact as if he only sees them EOW? He has as much power as she does. In your situation I would suggest he takes them full time and they go to stay with their mum when she's available, subject to her providing her rotas in advance.