To think she could have sat in a normal chair?

I always used to take a strap-on booster seat to friends houses if we were eating there...

you ask, or take a suitable seat for your child,

I think it’s unreasonable to assume your child can use another child’s seat. I always bring a portable booster when going to someone’s house. There are all sorts of reasons (child’s possessiveness of chair, messy eater and fabric dining chairs, parent not wanting to set a precedent) that may not be relevant in this specific case but are reasons I don’t make assumptions.

At the same time, I think your friend wasn’t being a good host when she saw you struggling and having come without a portable chair. That is also unreasonable.

Eating out anywhere is generally not a relaxing experience with a baby, chair or not. Sorry OP, you have a baby now, those days of easy, relaxing dinners with friends are gone for a bit.

Next time, bring an old vest with you for a quick DIY high chair:

https://www.tiktok.com/@ljflommom/video/7221550349444779307

You say 'no they don't' @Pippinsdiary
but a 2 second Amazon look at a portable high chair has 3,500 reviews on just one of them, so presumably very many people do

My 3yo would have a full on tantrum if I tried to put him in a high chair. I’m struggling to keep my 18 month old in his for goodness sake. I wouldn’t have expected to use their high chair but ultimately, it’s weird she didn’t think about you using it instead once she saw your little one in the car seat on the floor.

A lot of kids aren’t big enough for a normal chair until about age 6, but it depends on the size of the kid and height of the table.

I had twins so no one ever had a chair to accommodate us! Bumbo chairs were a game changer for me. Easily thrown into the car boot and light enough too. Otherwise there was one in the car seat and the other propped up somewhere or they just took turns. They often just sat on the floor to be honest on a towel or mat or on my knee.

It's not a big deal OP. I'd just forget about it. I do find it odd the high chair setting is still on though, that's really bad for a 3yr old who should be learning to sit properly. Its especially mad as they already have the perfect chair that they simply need to adjust, I'd have some understanding if they needed to invest in something new.

No they don’t OP 😂 people on here just want to disagree with you

Trip Trap is pretty much a normal chair adjusted to a 12 yo. A grown up can sit on it.

Well no. Which is why when out we took a seat for the baby.

OP has literally said numerous times it's still in the first, highchair setup. Not the later stages for toddlers/older kids. So no one is not understanding/ignorant of the Trip Trapp, the seat was still in the baby setup. We have one and it hasn't been in the baby setup for a long time for our 2yo!

A lot of rude people on here it seems. When you have a guest over, then you make sure they are comfortable. If you're inviting a 9mo baby for lunch it's not exactly a revelation that they will need somewhere to eat it 🤷‍♀️ and I don't expect people to pitch up to mine with a highchair. If I couldn't accommodate I would say at time of invitation, but otherwise I would make sure the baby had whatever they needed as my DC are capable of sitting on a big chair or something outside of their usual for a lunchtime when we have visitors.

No, as that's what having a 9 month old is like. At that age I didnt expect to have a peaceful civilised lunch with focus on adults. To make my life easier I used a portable booster chair but that still didn't give me the expectation I could focus on eating properly myself, more that my DC could eat properly. Maybe next time don't take the children

if she didn’t notice you were uncomfortable and a bit struggling then it’s rude she didn’t ask if you were ok, with daughter in your lap and would you like to switch and have the trap. Is she a robot or something, no empathy. No way I would not notice a friend being uncomfortable with a situation and I’d ask. Yes she’s rude.

I doubt a 3 year old fits into the baby seat

We used Trip Trap chairs from the children were 0-12 years. They could have used them longer if we had wanted. A grown up can sit on it if the chair is adjusted to it.

It's not a special chair. At all.
It's a chair which can be used from baby and adjusted as the grow up.
In Scandinavian it's a very common chair for families. It's Norwegian design I think.

We used to take this one on holidays https://amzn.eu/d/eCSpoq9

Highly recommend it.

My DS is 3.5 and massive. We still “squish” in into his Tripp trapp (he’s not at all squished) because he’s a bloody nightmare in a normal chair with legs and arms flying everywhere, standing up on the seat, turning around etc. he’s not a naughty kid, he just can’t sit still. We have asked him if he wants the high chair bits taken off and he’s said no. If we had friends over, no, my DS wouldn’t be turfed out of his seat. If I went to a friends house, I would expect to have my baby on my knee, as I usually do.

Can people genuinely eat properly with a 9 month old baby sitting on their lap

Well, no, but it's par for the course. I'm not saying the friend was right not to put her child on a chair, although she may well have her reasons, but I would say it was you who 'excluded' (your words) your dd by choosing the car seat on the floor so that you could eat properly.

I wouldn't think to put my 3.5 YO in a highchair now. My DD uses chairs exactly the same way we do now. She even uses our bar stools and can safely climb on and off. But I'd presume your friend just didn't think and there is a reason she asks her DC to, gets too distracted when she can get up and leave, makes too much mess. Try not to overthink it and don't let it ruin your friendship.