Wedding outfit for 12 year old - not dress!

[DaytimeIsCrazy]

Any suggestions for a tall 12 year old to wear to a very traditional wedding. XH is best man, groom is her uncle.
She likes the idea of a jump suit but will only wear very little plain colours (black, white, navy) and no pattern much.
I bought one but she didn’t like that it was thin frilly straps and low ish cut.
she also doesn’t mind the idea of trousers and top, but not sure where to start with that.
Any good ideas? AIBU to say she can’t wear joggers and an oversized hoody? ;)

New Look 915, or TK Maxx may be good places to start for a wide selection of trendy jumpsuits.

For trousers and a top maybe cullotes? They can look really quite smart, with a top tucked in, it would be dressed up enough for a wedding.

We had a family christening yesterday and my 12yo niece wore a sequinned miniskirt, loose vest top and knee high socks. I was a bit 😱 at the amount of thigh visible but she seemed happy with it...

How about something like this

www.next.co.uk/style/st153184/C70132#C70132

Hi. Would womens small sizing fit her or does it need to be kids sizing?

Some wide leg trousers and a blazer ? Zara or HM maybe

Culottes like this look comfortable and could be dressed up with the right top and shoes?

www.newlook.com/uk/girls/clothing/trousers/girls-pale-blue-ribbed-belted-wide-leg-crop-trousers/p/833251645

River Island have some in the girls section which might work? Black and not flimsy straps or low?

https://www.riverisland.com/p/girls-black-plisse-jumpsuit-471409

https://www.riverisland.com/p/girls-black-frill-scuba-jumpsuit-475663

It's maybe a bit blingy for her taste, but I've just bought this for my daughter. The navy's lovely, and she says it's really comfy to wear.
fhwt.app.link/VQBpRfwP4pb

H&M do a teenage boys suit in cotton and linen that's fine for girls too (well I think so and they sometimes use girls to model it:
www2.hm.com/en_gb/productpage.1059134001.html

It keeps selling out but so far they've always restocked it, sometimes in different colours. I've got the age14+ jacket in a dark blue - unfortunately the trousers were too tight!

How about a spaghetti strap dress or jumpsuit but with a top underneath

M&S womens size 6 fits my 11 yrs old. Worth starting there. Also companies that do a petite range.

We had a family christening in the autumn and my 11yo went with smart trousers, a velvet blazer and a patterned shirt, pair of girls brogues. Pretty much all from JL boys range. She looked smart and was comfy

Some great ideas there, thank you.
I should have said: she can for a small womens size or about age 14

BTW, River Island need much better photos (ideally with someone wearing the clothes) if they want to sell clothes.

These look quite comfortable and relaxed? Could be dressed up with nice flat sandals and earrings if she wears them.