@InTheHeatofLisbon
This is getting tiring now, you're cross posting to say the same things over and over.
Again, that is completely ignoring what his DD needs because OP said so. And OP repeatedly attacks the mother for not doing it her way.
It's nothing to do with OP saying so. Things change when you have a sibling and the father will need to help looking after both. This is true of any scenario where there is more than one child. She may have attached the mother for not doing so but I haven't, I've repeatedly said it's not the mums problem.
Nobody has said that, but I find it ludicrous that it's the 5 yo who needs to change their behaviour in that situation. It's the father!
You have said that the father should be there for the baby during the week and just focus on the 5yo on weekends, which in my book is shirking his responsibility to the baby during that time. Yes it's the father, I keep saying that?
But as there is now a sibling, yes the older child will need to adapt, as with any siblings.
Then why is the OP only considering her own children? But he's to change the behaviour of the only one in the house that isn't hers?
If OPs daughter required her mums full attention all night so OP could not care for her baby, then she would have to address her own child's expectations, but that isn't the case, it's his daughters expectations that are unsustainable in a house with three kids.
The resentment is clear, from OP towards the child and her mother. Including the nasty little "darling little stepdaughter" comment which was snide and unecessary.
Maybe so, but this doesn't change the problem of him not helping with one child so he can focus on another. That will breed resentment because it is unfair on the baby.
OPs DD shouldn't be inconvenienced by having to share a room until the DSD can sleep through. OPs words.
I think the older two should share regardless of whether the oldest girl wants it, but like you say that has been complicated by unwisely promising the step daughter her own room when it wasn't feasible.
*OP doesn't want to solely do the night feeds when DSD is there. (don't see why she can't tell her partner this, because it's him not getting up with the baby). OPs words.
XW needs to change what happens in her house to suit what OP wants. OPs words.
DD has to give up the room they gave her, because OP said so. OPs words.
If you can point out to me, anywhere, that OP even once considers the needs of her DSD I'll apologise and revise my opinion.
But she doesn't. At all.*
I haven't said any of this is not true, I disagreed with those things. But regardless of any of that, OPs father should be helping with his baby when his other daughter is there.