Help! Bleaching woes (for a friend!!!)

Was the hair previously dyed? If so a colour remover will help with the dark areas.
If not, does she want to lighten the dark parts or darken the light parts?
If she is still set on blonde you will have to carefully go through section by section and lightly bleach the dark parts.
If she is happy to go darker, an Adore dye in a warm brown would help to even it out, something like Mocha

I've got Adore on over bleach at the moment - the reddish browns do seem to fade very unnatural bright red/ orange/ ginger pretty quickly but a brown-brown should be ok I think? - I'm going to attempt a Castings box semi on mine in the next couple of days but not sure if it'll ruin my condition so I won't recommend that to your friend's daughter til I've tried and tested it! (Castings has peroxide developer so I think she'd at least have to wait a bit after 2 lots of bleaching). How ridiculous to deny a child a normal school life because of their hair! (I can see that they think they need to discourage other kids from doing the same but really, what are they supposed to do about it now it's done?)

I have used Casting with a much lower vol developer before with good results (I think it was 10, but could have been 7.5 vol) Try on a strand test, but the dark blondes definitely work with a lower vol (they came out slightly darker than the pic on the box)

Ooh so you swapped the developer it comes with for a a 10? I didn't realise you could do that (which sounds pretty dumb when I type it out!). Can you do that with permanent box dyes?

I tried the Castings anyway, in Chilli Chocolate - to be honest it has damaged it a bit, but only so far as it's really tangled when I wash it, as soon as I condition it it's fine. It's lasting pretty well but I'm gonna keep it topped up with adore mahogany and just do the roots in future I think.