Hi Sebol,
Lots of options for you and your daughter.
A spreader bar with the hook removed (ground off) and a stainless steel eye bolt going through the spreader, then use a Witchard quick release shackle tied directly onto the depower line, this will bring the whole thing to within a few centimetres of her body.
Some small kites fly really well in light winds like the 4m Ozone Catalyst. I have a few small 4m kites like Airush DNA's kickin' around the shed but you will need to add a sliding stopper to the bar setup as they will luff if you let the bar all the way out and she won't be able to reach it again.
Biggest issue you will find is harnesses small enough, and footstraps and boards small enough. At 25 kilo she wont need anything bigger than 110cm x ~34cm. North Footstraps in the small ladies size will be perfect for her pixie feet.

ION in XS will be fine for here around the waist, they barely fit around my thigh and I aint carryin' too much weight

The board you need is rarer than rockin' horse dung. An Airush Airforce 110 is ideal, or make a custom for her. Guys Like Dan at Cardboards could make you a custom small and flexible enough, or just make one yourself out of ply. Scale down the dimensions of a North Crossride 129. The board hull is the least of your worries, the accessories for the board are more critical.
Give me a call if I can be of assistance.

Cheers,
DM