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

The point is her resentment over money shouldn’t be focused on what he is spending on DSD.
Clearly this mixing of finances isn’t working.

OP needs to put the SDC stuff aside and focus on asserting her own boundaries so that they separate her finances. This should include : Stop paying (herself) for SDC. Insist her partner shares expenses for their child. Equal division of bills and rent.

Rent and household bills should be split between both adults. New baby expenses should be split between both adults. SD costs should be paid for by the father surely? He would be paying for his existing daughter with or without the OP. If he has less disposable income than the OP that’s a consequence of having a previous child to pay for. OP should be saving her excess cash separately with a view to buying a house for her and her new baby at some stage. And not marry this man.

As well as paying for the weekly food shop (roughly £240pm) which is roughly what half the rent is.

Half what the rent should be at market value, or half after his family have subsidised it? £480 seems an extremely low rent!!

My opinion is that ypu are getting a very good deal.

You clearly feel alone in this pregnancy with talk of buying everything and needing to support yourself during your maternity leave. The deeper problem is that you can’t rely on him as a provider or equal partner.

You can move past financial difficulties in a relationship and the Monzo account is a big step forward BUT he needs to be honest about the extent of his debts. You’ve worked hard and are financially savvy so you need to know his situation as it could hamper/change/delay your plans for life you want to build.

Run. He's got debts. Pays minuscule rent and still expects you to fund his daughter and doesn't contribute to your baby.

Leave before it's too late.

you also wrote this,

ӣ50 so far has been spent on clothes, these clothes will go back to her mothers house and we never see them again, hence why 2 weeks later we are required to get more clothes. And nothing is being contributed to a new baby on the way.
I have subbed money in the past, and paid large amounts for DSD and recieved nothing in return…
This was never an issue, until my DP was not contributing to second child”

you literally say his spending on DSD was never an issue until the new baby and now you are questioning and resenting it and baby is not even born.

As I said you need to get out of this mindset. Psychologically Separate your resentment over what he spends on your step daughter from your needs in terms of what you need him to contribute for the baby.

Make sure all finances are fairly split including the rent. Stop spending on his daughter. Agree with him what baby reasonably needs (now or later) and insist it’s divided

Don't go on expensive trips then. He wants to give his daughter the loveliest time, it is guilt too.

Last weekend my DP said we needed to go shopping again as DSD “had no clothes” so although unable to contribute to anything baby related was willing to spend another £50 on clothes that really were not needed.

Guilt again.

He needs to allocate a percentage of his earnings to the upcoming maternity leave.

You definitely both hopped in this relationship without much thought.

Remember his DD is a child, don't be resentful towards her.

I think you just need to be recording all bills and expenditures. Get a notebook and just write it all down, then work out "who owes" at the end of the month. It sounds like a complicating factor is that your family were giving you free housing so it's hard to calculate how much you "owe" towards the rent. Beware of how he calculated your "contribution" after you have the baby because some men see the woman as contributing nothing when she is looking after the newborn and not earning an "actual income." Make it clear beforehand that looking after the baby is a contribution equal to whatever you were bringing in monthly before that (or more) and that you will not consider yourself to be accruing any sort of debt to him during your maternity leave, nor will you be living off of your savings. You will be expecting him to contribute by supporting you during the months you can't work because you are looking after the baby you BOTH created.

OP I think you're getting a bit of a rough ride from some PP here. You sound like a supportive DSM but your SDs expenses are definitely not yours to bear.

You'll never get a fair ride as an DSM on here sadly.

That aside, you should really consider moving in with your parents again if you can. I think you're setting yourself up for a lot of disappointment and anguish here.

Perhaps you haven’t read the full thread and lucky enough not to be in OP’s position.

OP is pregnant and needs to save for her maternity leave, DP (who won’t show OP his outgoings) is squatting money away and not thinking about the future, not putting any money towards new baby or thinking about OP’s maternity leave. Why is it OP’s responsibility to pay 100% for unborn baby and a lot of outgoings for her step child when DP can’t be bothered and would rather spend on other things?

OP didn’t have any issue paying towards SDC before she got pregnant; it’s now come to light that DP isn’t interested in investing for future or helping out with costs for baby. The reason OP mentioned the clothes for SDC is because if DP is struggling with money - shouldn’t he be prioritising his spending? Why is he spending £50 on clothes that DD doesn’t need when he has a baby coming who NEEDS items

But the CMS payment will change as there is a second child that he needs to provide for.

OP, you wrote this:

”Last weekend my DP said we needed to go shopping again as DSD “had no clothes” so although unable to contribute to anything baby related was willing to spend another £50 on clothes that really were not needed.”

You can feel your frustration in this post. And I would be annoyed too. Can you go stay with your family for a few days, get looked after and get some head space?

FGS. OP isn’t putting her step child against new baby

she absolutely is. She’s complaining that he wants to spend £50 on clothes for his DD because he wont contribute to stuff she’s bought for the baby.
Shes also raised the issue of child maintenance.
(Note the baby isn’t even born yet and I’ve never known anyone to buy this much 4 months in advance! But besides the point)

are you still saving for a house?
the cheap rent will stop one day and it will be a shock when it happens. I’ve seen multiple people come unstuck with this and feel real resentment against the person who has done the favour

What SD’s mum did is totally irrelevant. Stop trying to create drama where there isn’t any.

Do your own risk assessment. You're an intelligent woman. What does the worse case scenario look like to you? What actions can you take now to pre-empt that? What securities for yourself and child can you put in place?

He should be paying for activities, don't join them on expensive days out, an extra adult admission fee and food adds up.

Are you expecting to join in, eat, drink and not pay.

He needs to look into free local events, picnics in the park.

This is why I think bringing children into situations like this never benefits them, it's all about what the adults selfishly want.

Op firstly you foolishly decided to move into a home with no security for yourself or now this baby. If he kicked you out then what? You are 'saving' to a house with no secure job and living in a home that you have no rights to.

Then there's the SD, who needs clothes which her father can't buy. So that's taking your money away from your baby to another child.

Then there's this new child with parents who are already having issues financially and otherwise. What a mess really.

I would be very careful about it becoming ours- there is no transparency on his spending or debt. A joint account for household bills would he as far as I would go.