Looking for a non-wire, possibly multi-way, bra, or other recommendation.

[HungHung]

My teenage daughter has bought this yellow River island dress & is looking for a non-wired lingerie solution. She’s a M&S 34C. Any recommendations? The dress has a plunging neckline, lowish back & spaghetti straps. She plans to lift the dress over her head & wear it as a halter neck; she feels it’s a little too plunging & revealing for her liking.

I would just go bra less. A bit of tit tape or rock tape for some lift, depending on wear it hangs.

Wonderbra do a multi-way ultra plunge bra which would technically work but it’s ultra reinforced and gets clammy when dancing.

if she pulls it over her head, isn’t the waist from going to be in an odd place?

The dress actually looks fine with it over her head. The waist part is under her bust & the dress flows out. I would need to readjust the back crossover straps (just a couple of stitches) to make them slightly shorter, which solves the back of the dress being a little longer than the front.

I thought all Wonderbras were underwired?

I was going to suggest something like this www.uniqlo.com/uk/en/product/mame-kurogouchi-plunging-wireless-bra-450446.html?dwvar_450446_color=COL30&dwvar_450446_size=SMA005 but that won't work if she's wearing it as a halter neck.
The wonder bra strapless one could work. Or maybe the M&S wireless strapless one. I think her best bet might be to go braless.

A wireless solution for what you want doesn’t exist

there is a deep plunge and a low back. You will have no support without wiring if you don’t want the bra exposed at all. You can get wireless bandeaus but you will see it at the plunge and around the back

she needs to go braless, or use body tape for support and lift. There isn’t any other way.

This is the only thing I could find for a wireless halter low back bra, but it's expensive and not padded. If she wears the dress as a halter, it'll have to be with a halter bra and use those back conversion strap things, like this. Could she wear it normally with a low back bralette so there's more front coverage? Something ike this or this.