Sadly, there is no perfect solution and you will have to compromise somewhere. Isofix seats don't come in sizes that will last big babies until 7years or older. Same is true for almost all (as far as I'm aware) rear and front facing ones. I was in the same position and very stressed about it. My LO is also big (95th percentile) and I went for the Britax Mac Safe Pro as he will safely be rear facing in it until he's big enough to go into a high back booster (7-ish years). Not Isofix though, my understanding was that Isofix is beneficial when you want to move the seat between cars often. I wasn't aware of any safety 'concerns'
I was close to buying the emerald as well but didn't like that LO would have to be switched to front facing quite early
https://www.kiddies-kingdom.com/birth-11-yrs/53927-amana-siena-twist-360-spin-all-stage-i-size-group-0123-car-seat-graphite-exclusive-to-kk.html We’ve just bought this one as it has really good safety ratings and is meant to go up to 11 years
@Ina I hadn’t seen mention anywhere of when you have to face them forward? I intend to have my daughter rear facing for as long as seems comfortable
It's not on any website but when I went to mamas and papas they told me that the rear facing set up is only good until 105 cm. Then you have to change something (I can't remember what, the harness?) and it has to be forward facing. For us that'll likely be at 3.5 years
@Ina oh really? 3yrs seems so young 🫣 I see so much on social media of children squished rear facing and they’re like 4/5/6yrs !! I’ll look into it though thank you x
We got the Cybex Sirona T (at 12 months) after the Cybex Cloud and you can use it on the same isofix base as the Cloud. They say you can use until 4 years. My LO is 16 months and sits rear facing but the Sirona is both rear and forward The Sirona is both rear and forward facing so it might not last until 7 years but maybe will last longer as you have both options.
The Silver Cross Motion 2 lasts from newborn until 12years (ish). It will rear face until approximately 4years and then you use it with the car seat belt whilst forward facing. With our first child we had the cybex cloud until 14months, then went onto the Sirona z until just before she turned 4years, and she is now in the silver cross balance. I hope that helps. Just to add my little girl grew out of the Sirona sooner than the weight height recommendations as she felt really squashed in and she’s on 50th percentile for weight and 30th percentile for height. If you’re child is on the taller side you may find they grow out of it/not feel so comfortable in if right up to 4years.
We had the same issue. We ended up getting this one, think it ticks all your boxes. https://www.mamasandpapas.com/products/maxi-cosi-emerald-360-s-car-seat-50462h700?utm_term=43568969580709&utm_source=google&utm_medium=cpc&utm_campaign=uk+-+shopping+-+travel+-+pmax+-+priority&gad_source=1&gclid=CjwKCAiAp4O8BhAkEiwAqv2UqA6MkoNYwSKNsUMjOaaKuObj4ep0vO8APspfW9N-uoFnZ_eGzdCkKBoCRw0QAvD_BwE