AIBU not to reduce my children’s Christmas presents to match stepchildren’s?

This.

Why can the gifts not be staggered?

TBH, when I was in this situation I used to book something nice for Christmas Eve with my kids (like a mini treat Christmas) and then SD would arrive in the evening and everything would look equal.
SD mum is like me and would also of done the same.

Bloody ridiculous giving them expensive presents anyway… but that’s besides the point. How will it even out as they get older? Will you eg gift your kids driving lessons and a deposit for a property and your DP can’t or won’t do that? Are you both on vastly differing salaries? Does your DP spunk money up the wall on his stuff? It just seems very strange that you have more money than he does for presents. Which are only really material things when all’s said and done.

As others have said this is not a blended family. You cannot and should not treat them all differently but that trend already started over the bedroom allocation.
This should have been discussed and agreed on prior to you all living together. There is no easy solution to resolving it.
Just give them all equal amount on Christmas morning and add to your children's later when the others have gone to their Mum's.

This.
Doesn't sound like this arrangement benefits your children at all.

I agree with others who have said that if you consider yourself a blended family then all children should be treated the same. Imagine how your children would feel if it was the other way round and they were opening a few, low cost presents where as your dp’s children were opening hoards of high cost presents. I think you should spend what you want to spend on them but agree that holding presents back for them to open when your dp’s kids are with their mum is a good option.

(edited as I realise OP said she is a sole parent to her kids)

Stupid reply. They are only together for the morning, and for all you know they might love each others company.

Your DP is wrong

At first I thought YABU, but reading your post in full -

At your house your step children will only be getting presents from their dad. They will get more from their mum.
You have already decided to spend your money on getting them Christmas Eve boxes.

So no, absolutely you're not being unreasonable. If you were to top up your stepkids' presents they'd likely end up with more than your children, because they will get more from their mum. I think your partner should explain this to them in advance, and put it to them that they are lucky because they get to celebrate and open presents twice.
As an aside - I think it's a bloody shame that your two children are in the home full time and have to share a room, but the step children who are only there part time get their own rooms. I hope you're not doing the financial heavy lifting in this relationship.

Yep! Save some for later!

YABU for forcing all these kids to spend Christmas with people that aren't their family under that hideous 'blended' label. Since you're insisting on doing this to them, you should treat them all the same on Christmas morning.

This is the answer. Just have some later.

As PPs, ages are really relevant here. I think it's also relevant whether you're doing the FC thing or not, and also what kind of presents they are. The types of presents will determine whether you could reasonably even up the amount of presents without changing the budgets - for example, your partner could buy things second hand or get high street brands of the same thing rather than designer, etc.

Tbh if your step kids are old enough to need their own rooms I think they’re old enough to understand.

So just explain it to them in advance - they’ll get gifts from their dad and then separately from their mum.

Your kids will only be getting gifts from you.

So when they look at the gifts in the morning it will look like your kids got more, but that’s because they’re getting all their gifts then, whereas the stepkids will also be getting more of their gifts later. Overall it will end up equal.

My 9 year old would understand that, it’s not too difficult a concept for them surely?

Give them all the same on X-mas eve/morning. Once your step-kids leave to go to their other parents house you can then do more presents for your own kids. This way in future years when they presumably will swap times then when they come to you guys for dinner etc you already have laid the ground work that means your kids aren't watching them open gifts while they had all of their own in the morning.

She isn't making it complicated, he is.

You’re not really a blended family are you? If you were you’d not be behaving the way you are around presents.

You're not a blended family, you're two families that are sometimes staying in the same house.

There is always inequality in these set ups. If your partner wants equality he shouldn't have moved in with you.

Just give your dc some presents later in the day as other posters have said. It’s really not that big a deal unless you make it one. If they still believe in Father Christmas make a game “silly Santa has hidden some presents” - it’s only complicated if you make it complicated.

A few factors are to be considered. His kids are older and the norm is that the older the child, the more you spend because what they really want is usually more expensive.

Saying that, if there is a big difference in age, the elder might not care that the younger ones are getting three books whilst they get one. Closer in age, with youngest getting the latest phone and an iPad, whilst the older are getting an older phone version might be an issue.

And then comes in what they get with their mum. If they get the phone at their mum and dad gets them the iPad, they might not care.

There is also their personalities. My kids never cared if one got more than the other and same with their step siblings. They were not the envious type or children who compare, so it was less an issue. For children who do gold a strong sense of justice, it might be very hurtful they are getting less, even if all together it is the same.

Lastly, the experience. If they've open their presents, and they then gave to spend the next half hour watching the others open them with the adults building the fun and excitement, they might feel inadequate.

Consider all those things with your OH to decide all in all how you can ensure Xmas is a nice experience for all 4 children.

Whats the real difference here? Are his kids getting a book and yours are getting iphones? Maybe reign back Christmas slightly if it is a very significant difference and go all out for your DC birthday.

How old are all the kids involved? If his are teens they’re old enough to understand quantity vs quality eg 3x £20 presents vs 1x£60 present. They’re also old enough to understand that they’ll get more presents later at mum’s whereas yours won’t.

You could always hold back some of your kids’ presents for them to open after your step kids have gone to their other parent.

My gut reaction to your title was that you'll be setting yourself up for a miserable Christmas if whining of you don't get the same amount for both, but having read on I completely see your point.

I would just ask DP to give his kids a heads up about it, along the lines of "the others are getting all their presents here as they don't go to their dad's, whereas you are getting half here and half at your mum's because you go to both houses".

ETA how old are all the children in question?

Christmas presents are just the tip of the iceberg - and I say this as someone who only does inexpensive presents - this is not the only way in which your children are suffering by having another family imposed upon them. Will he want you to pay for his kids’ school trips, driving lessons, university tuition, flat deposit and wedding? They’re already sharing a room when his part-time kids have one each. Put your children ahead of your sex life and stop co-habiting.

In this situation, can you please explain to me exactly how your kids benefit from this arrangement? Because from where I am it seems they don’t, at all. They have to share a room 100% of the time while their step siblings have two bedrooms each. The living situation hasn’t bright now money into the house, in fact it’s cost more so less in the pot for them. You are getting sex for your part of the deal so I’m hoping that’s at least good. Your kids though? They really got the shitty end of the stick and now he wants to take away half their presents