If he's giving her the money does that mean she buys the gifts and takes all the credit for them?

They're not married anymore, why would they give joint presents? They don't have a shared bank account. They should both be getting separate gifts.

A couple things here:

I agree with the others. There is no joint Christmas anything. If the kids want bikes, okay fine, but that's it. No more large and expensive gifts and no collaborating between BM and DH. This stuff needs to be kept separate. There should be a discussion between you and DH about budgets for Christmas so your kids don't get a $20 Lego set while his kids get an $500 Xbox, if you get what I'm saying. There needs to be mutual understanding that while you are responsible for yours and he is responsible for his, there still has to be a set standard across the board or members of this blended family will start to harbor serious resentment. 

As far as the bus pass goes, would SS be emancipated in the eyes of the courts due to college attendance at this age? In many states in the US, once the skid is 18 and out of high school, financial responsibilities are done. There are some states that go until 21 though. If SS would be considered "aged out" in your country, I would agree to let him stand on his own for the £46 bus pass. It's good to teach him some financial responsibility and that is a small amount to expect. If he would not be aged out, then I agree with picking up the cost every once in a while. 

In some ways, he contributes to your children much more than you do to his. He gives you half his salary. In a house where he has less than half the costs. You bring with you four children, he brings two. He doesn't pay out support every month, but do you pay or receive?

it sucks that the kids have parents with different earning abilities or spending habits, but that's life! Unless the half wages he's giving to you doesn't cover 1/3 of your bills (his 2 to your 4) I don't see that you have a reason to feel cheated. His kids have two parents pooling their money for Christmas. You seem to be doing it on your own (whether you make less money, or you also don't get support, or just that yiu have twice as many kids, there's not as much to spend on yours). Yes it may cause resentment in a blended family, but it may also be an opportunity to teach basic economics. You can only spend the money that you yourself earn. You don't get to spend anyone else's money. Your kids will learn the value a dollar just as his kids will. It's just that he seem to have more to spend on them.

that doesn't mean that the two of you can't agree to some kind of limit at Christmas. But if he and his ex have always spent like this at Christmas time and he's happy to do so. I don't think he's wrong. As long as he's paying his bills, his discretionary money is discretionary.

So, SO does not pay anything.

For damned sure if BM is getting all of the Gov't support for the failed family spawn, not one cent of marital income from your marriage should go to BM.

As for gifts, BM does not dictate what you and SO give as gifts.  

Since BM gets significant child support from the Gov't, she can buy the bus passes.  You have every expectation that every cent of income you and your SO earn is marital income.  There is no CO, so.... no money goes to BM other than her Gov't child support stipend.

Do not make this overly complex. Keep it simple.  100% of SO's income should go into family accounts.  

Keep in mind that if you receive the Gov't stipend for your 4, that goes into your family finances as well.

I am not saying that there has to be equality in cost of gifts between yours, his, and your joint child.  But for sure, the gifts for his failed family progeny should not cause any burden on your household.  Particularly when demanded by his XW.

I'm split.  the bus pass is somethign both parents should pay. the kid is 16.  that she has paid last 2x... it's your husband's turn.

The christmas?  your SO needs to spend within his means... and he should be spending equitably to his bio kids.. if that means more than your bio kids get because he and his ex can afford more/  so be it.. but he has 3 kids... each get a share equally.. and that is his obligation.. so your little should have gotten 500K.. from him.. plus what you would spend.

he needs to dial back christmas if he is broke.

Why does everyone think a 6 month old and a 16 year old need the same amount of money spent on them at Christmas? That is ridiculous, especially when spending gets into the hundreds. Fair doesn't mean equal. I think my youngest (who was 6 months old) got a soft toy and some chew toys last Christmas while my then 15 year old sd got $300 cash.

Katy, you've got 5 kids your husband only has 3. As I see it you spent 1000 on all your kids and he spent 1000 plus whatever the baby got. Seems like even spending, just you have more kids to spread your money around. 

As for your birthday, that sucks he didn't do something special for you. You should make sure he realizes that you're disappointed so that he can try to do better next time. He should have managed his money better, and you should have been a priority.

If you are spending more than half your income on the bills then perhaps your husband needs to be providing more to cover bills. If you feel resentful that he pays less than you, then you two need to sit down and come up with a plan so things feel more even to you both. Paying a percentage of income is not the only way to split bills. 

The bus fare would be something that I might get my kid to pay, but it is a parenting decision for the bio parents to decide between them how they want to teach their kid about finances. You can express your opinion to your husband but it is his decision to make at the end of the day. Luckily in this case it is a minimal financial cost.