To think this dad is being very rude and inconsiderate?

This ^^

Dad prob thought it best he was going anyway as ds is 8 is quite young and for some rides I guess an extra adult would be needed if you already have 1.1 ratio of kids for your own family on rides. I wouldn't be happy sending my 8 yr old to a big theme park with parents I don't know very well, so it makes sense he wants to go to make sure ds is ok with the rides etc but without letting his bf down.. the follow on of taking 2nd Child and paying for him prob didn't occur to him as an issue because he could keep your youngest company. I think your overreacting here, he is paying his own way - I'd tell him to make his own way there though.

Um can’t the 6yo go on with the dad? I don’t know what sort of theme park this is but I’d want to keep an eye on an 8 yo at somewhere like Chessington. It’s a really huge place and some of the rides are a bit scary. The OP might actually be grateful he is there, especially if any of the rides say the kids have to be accompanied by an adult as the OP’s DH and this dad can then sort that out while the OP stays with the 2 year old.

Utter nonsense! Are you 'one of those mums' who brings uninvited siblings to birthday parties? If so, stop it! It's bloody irritating (and rude!)

no and it doesn’t sound like this dad is insisting either - he suggested it. Maybe he thought it was just the dad and DS going. Just say no, there’s no room.

Actually for DSS party one of the dads did offer lifts to a couple of other children as he had extra space in his car. Which was very helpful and very nice.

@TheGoodEnoughWife I think it depends how old the friends younger sibling is tbh in comparing this. It sounds like younger sibling might be older if the dad didn't want to tell them they couldn't come. Let's be honest the two 8 year olds will want to sit on the rides together. The OP 2 year old will probably just enjoy being at the park, going on any rides that are suitable and would have to sit with a parent. But if the other sibling is say around aged 6. Will they get upset when their older brother isn't going to sit with them. Will the older kids be expected to accommodate him which then isn't fair on the bday boy!

So no I don't think it's mean to say no! Kids need to learnt they cant always do everything their older sibling does and dad needs to accept he has the younger one by himself that day.

Maybe dad was thinking it was only one adult taking both 8 year olds and therefore room for him and his other son in the car? Does dad drive and maybe thinking it's a way for him to take younger one if he doesn't drive?

Yes that’s a really good idea. Most rides are in twos anyway so LB will probably go with dad for most of them.

If the dad wants to take his younger son at the same time that's no fuss to you. Just say your family plus older child will go and do your thing. The bigger boys will be going on different rides to the younger one. You can say we will treat the eldest to lunch and snacks. He can pay for the younger one.

This genuinely wouldn't bother me.

The older boys can go off on their rides and maybe it will be nice for your youngest to have a little friend to go on the kiddie rides ride.

I'm not seeing a problem.

The dad isn't "cheeky" for asking. But if it doesn't suit you for any reason just decline.

But surely it's nice to foster good relations between your two families if the boys are best friends.

It wouldn’t. It would be really inappropriate for you to tell someone else’s child information that they will find upsetting/disappointing.

If the OP did then she might find the dad saying Mark is sadly also unavailable due to a family thing and then her DS can enjoy a solo birthday. You can’t have your birthday at a public venue and start moaning if other people decide to go the same day.

This. Great idea.

Did those parents also insist on riding with their children in your car? And do you drive a bus by any change?

Who the fuck thinks it's ok to insert themselves and their child into somebody else's life like this? You can only imagine the thought process 'Oh, they won't mind. It's only me and younger DS. They're going anyway'.

Well, guess what, Mark's dad? Not everyone is delighted by the prospect of your company on a family trip (in their car!)

When you tell this CF that he's not invited, remember it's because it's a family trip and you (very reasonably) don't want him there. The size of your car is irrelevant, plus he can work around that if he's prepared to drive his own. How about something like:

'I hear you spoke to DH about DS's birthday. The thing is, it's a family trip. DS invited Mark. We're not planning on anybody else joining us. We'll pick Mark up at x o'clock, yes?'

Sounds as if the other dad is controlling someone else's arrangements and also may not have full confidence of your supervision of his son at a theme park. Two toddlers is also going to jam up the works as is going in one car. What about if someone needs to leave early? I would have a chat with my son and also with the other dad as you are not happy with 'his' organising your son's birthday. Could you take your family to the theme park and perhaps the friend come over for a little party? I would be on the ceiling with fury to be honest!

He’s not inviting himself, he’s going to the theme park. It’s perfectly normal for parents to stay at a public event - they’re 8, not 18. Not sure I’d be entirely happy just leaving a young child there and there’s nothing to say that you have to go around with him and the younger boy. Presumably the DS and friend will go together on rides and the dad will go with the younger brother.
At my DSS birthday party recently, at an adventure park, about half the parents decided to make a day of it, many had brought younger siblings along and they all paid for their own tickets. Nobody accused anyone of inviting themselves to the party.

It's very rude to invite himself, an adult, and another child to somebody else's birthday event.

@Startinganew32 that's pretty disingenuous.

I think this would be the perfect reaction

The OP can’t police who goes to the theme park. If the dad wants to take his younger son there too that day, so be it. Appreciate that having the younger brother there might be annoying but I’m sure he will get over it and I don’t buy that it will ruin his birthday treat.

If the dad is just planning to go around with the younger sibling then I don't think that's rude, it's a public place not a private event and there's nothing OP can do to stop him going. Maybe the child is only allowed to attend on those terms because his parents are not comfortable with it. I've been at children's parties in places such as Hollywood Bowl and Ninja Warrior where a parent has stayed with other siblings and that hasn't affected the party as they stayed separate.

Maybe he misunderstood? Just be straight with him and say what your sons wants. Maybe he is aware it's just the son involved, but feels uncomfortable letting him go and is offering a solution?

The transport issue seems to solve the problem, as you can’t fit all of them in!
“Sorry Mark’s dad, don’t know what Husband was thinking! We can’t all travel together as we don’t have room in the car, it’s a normal Ford Focus not a people carrier. We’ll pick Mark up at 9 though, and maybe see you and Little Brother there- we could meet for cake and candles at 1pm”

You’re not excluding them but you’re not facilitating the tagging-along. And by 1, Mark might quite enjoy seeing his dad.

My DD was invited to a theme park with a friend once. We had a similar response - yes, she can come, but we are all coming along. For us, it was that my daughter wanted to go but would.not have coped with such a long day without us and had some additional needs that the parents, while aware, didn't really get. In the end we drove as a family, met them there, then left DD to go round the park with best friend and family while we went round on our own. It meant that if there was an issue, we were on site and able to respond quickly.

Perhaps have a conversation and clarify if they are intending to spend the day with you or whether they could go off on their own and just meet at the end of the day? There could be a reason they want to be nearby and they might not necessarily want to directly explain it.

Be prepared for Mark to not let his older son come if you say no, then your son would be more disappointed. I would just say more the merrier and make the best of it (obviously if you can’t all fit in one car you will need to go separately)

They're taking their 2 year old because he's their kid! That's fairly obvious and doesn't need to be justified or explained.

Autienotnaughty - this message is good.

"Hi I think there's been a misunderstanding? We invited mark to come with us for ds's birthday treat . Perhaps you could take mark and his younger db another time? Sorry for the confusion, let us no if you are still happy for mark to come. No worries either way. "

But obviously put 'know' and not 'no' 😉.

As a parent I would prefer to be there with my child and perhaps the child wants his Dad there? But they should travel separately.

I think you should accept the extra people.