Erm, if you split up with him, you would HAVE to pay for nursery. If he is a SAHP to your DD, then he is ignoring his financial responsibilities to his FIRST child.
I think that while he bears a financial responsibility towards his first child, he should be at work. If that means YOU being a SAHP, then so be it.
If you couldn't afford Nursery fees AND maintenance for your DP's DS, as a family, then you shouldn't have had another child, should you? The maintenance contributions to his first child should come first.
When you already have one child, you should think about the financial implications of having another one BEFORE you have them. Your DP obviously didn't.
His maintenance for his DS comes first, not how expensive nursery is for your DD.
He is depriving his DS of financial support by being a SAHD to your DD. IMO that is reprehensible.
And as for withholding maintenance until he saw his DS - WTF?! Children are NOT pay-per-view, where you only have to pay if you see them! Maintenance and contact are, rightly, separate. It doesn't matter whether he never sees his DS again, he STILL has a financial responsibility towards him.
I am utterly DISGUSTED that you are whining about how your HOUSEHOLD income will have to cover his maintenance, when you are admitting that he is not in work because 'nursery is too expensive'.
It's NOT your money/ his money when he is SAVING you the cost of nursery fees by enabling you to go to work by looking after your DD rather than being employed himself! It is then HOUSEHOLD income.
If you don't want it to be HOUSEHOLD income, then tell him to get a job and support his DS himself!
How DARE you moan and complain that your HOUSEHOLD income will need to be used to support your DP's DS. If he went out to work, then he could pay. As he looks after your DD, he isn't in work, so the HOUSEHOLD income should cover it.
YOU chose to get into a relationship with someone who already had a child, you have to accept the financial and emotional responsibilities your DP has to his DS. Tough shit if it makes you hard up paying maintenance. If he can't pay because he is a SAHD, and you don't want to (you will have no legal way of recouping those payments if you and your DP split btw), then he HAS to stop being a SAHD and get a job. Any job. Even if it pays less than your nursery fees. You should have thought about the fact that maintenance comes first, everything else after. Before having a child with your DP that he obviously can't afford to look after, as it is stopping him from financially supporting his existing child.
And I hope you realise that your DP can lose his driving license, have his passport confiscated, and even be imprisoned for non-payment of maintenance. And those powers are going to be use much much more as of April next year.
You'd have to pay for nursery if your DP was in prison for 6 weeks, wouldn't you?
Your DP is a worm. And it won't be long before he does the same to you. Hope you're ready. Because I can't see you getting maintenance out of this reprobate.