My partner, my DSD, our unborn baby and our financial split/responsibilities

Once you have your own baby, your priorities are going to shift entirely and you’ll put him or her first. Sacrificing your own stability and finances for your partner and his kid won’t cut it anymore.

It’s best to get this all out and a budget in place ASAP or I see you leaving him pretty sharpish. He’s taking the piss massively.

With no where with your own name to live and being utterly reliant on this boyfriend for your housing where he has no rental agreement, you have bigger problems than paying for your boyfriend's daughter. Are you paying what he says you have to pay because you're fearful he will kick you out? Because he could and rightly so for any reason.

You said you had SD for all the weekends plus a week in January, that’s 13 days out of 31. So he’s paying more than he needs to his ex whilst you pay for SD in his house.

That should make you angry.

Is this a serious reply? OP is pregnant, unmarried, living in a house she has no rights to, and is having to fund her own maternity leave, but you think she should, be prioritising buying things for HIS daughter because otherwise she's a 'poor poor child' and OP must begrudge her (even though you cant back this claim up)? Ridiculous.

3 months isn't close to enough. What if you can't go back to.work at all, let alone early at 3 months? I couldn't, despite all the plans. What then? Who's paying for childcare?
How will you pay a full rent if and when this nebulous arrangement with his family member falls through, or you split and he kicks you out?

You won’t need a cot for at least 4 months, formula and nappies are bought as you need them, you definitely won’t need a baby gate for at least a year. You’ll likely get baby blankets as gifts.
You’re over thinking this, and spending far too much money on the DSD - I really can’t understand how she’s costing you so much! In addition, you’re living rent free.

Does the CMS change when the baby arrives as he is now responsible for 2 children?

He doesn’t expect to support you and the baby at all. He’s got “a mouth full of promises and a hand full of nevermind” as they say.

I tend to agree. I have joint finances with my husband but it took years to build that trust. Turns out we are both tight arse savers! But I would not risk assets with somebody like this who can’t even be honest about his spending or debt when you live together with a baby on the way.

You're making stuff up again

Also adding to my comment your DP is spending money like no business knowing he has a girlfriend that he will need to support on maternity leave. Yeah…. Maybe just leave.

Pull right back on leisure activities

Seems you all can't afford them right now

In the whole of 'The Little Glass Slipper' by Charles Perrault, neither the step-mother, nor any of the step-sisters ever said 'I begrudge your daughter'. Not once. It is called 'implied from conducts'.

This is really sad OP and I worry you’re in for a big shock when you’ve given birth. From what you’ve said your partner should be able to cover all the household costs whilst you take a reasonable maternity leave. Being forced to go back after three months because he’s pissing away money on nothing is not acceptable.

I bet SD’s mother wasn’t back at work after three months.

It sounds like you have your s**t together money wise but he doesn't and you live together and are having a baby so you both need to be on the same page. You will end up resentful, it's quite weird and inappropriate that a father is not contributing to their baby to be.

The thing is OP you sound like you want to get the finances sorted which is the smart thing to do but unfortunately DP needs to be on board.

I worry about your future, it’s not just the baby items and the first year of life it’s being able to afford both his DC for the rest of his life. It’s not just “ok I’ll put into the pot before baby arrives” it’s financial security that you will need for life. Do you want to get married? This man seems like he wouldn’t be able to afford to propose let alone make you a wife.

DP has 2 kids now, why is he spending money like he’s a single man with no responsibilities?

The only way to make this work is for DP to lay every card on the table, to agree on a fair plan with finances going forward. If he won’t even give you that then you need to leave OP.

I think the joint account for household bills would probably work best. Then you know what you have left over each month - the rent and food shop comes out if that. Also means you keep access to anything extra you earn and save.

100%. OP shouldn’t be subsidising SD in her home but she definitely shouldn’t be subsiding her in her mother’s home.

Buying a house is a fantasy for him right now. If he won't share the details of his finances it's because he knows the debt is high enough that you would realise that.
The joint pots are useless unless he actually has the money to fund them.

When your baby arrives this issue will be worse, because you will be 100% funding anything you want to do with the baby, anything the baby needs and anything you need as a result of pregnancy changing your body.
He cannot afford any extra expenses right now and will expect you to Cover these costs so he can continue to cover his child support costs for his first child.

One way or the other, you will be paying even more than you are now pretty soon. So I would be insisting on that transparency if I planned to stay in the relationship.

Have you discussed what would happen financially if you were not able to go back to work right away after the birth?

I only have one practical piece of advice, from experience, @Newmum770 whatever clothes your dsd arrives in, dress her back in them when she goes back.
I wouldn't like to add up the cost of the clothes I bought that I literally never saw again. I was young and dumb. Thought I was doing the decent thing. Doing the best for dd. Nope! I was being taken for a mug. Don't be me.

I agree with this. This man's long-term goal will be to have you paying for and mothering both of his children.