Box dye over highlights

[toomanyplants]

DD (18) has recently had hair highlighted, blonde/caramel, now decided she doesn't like it and wants to go brown again.
Can she just put an olio box type dye over the top or would this damage her hair?
I've heard that going darker isn't as harsh as going lighter.. but I'm a bit clueless on these things, any hairdressers that could advise please?

I’ve done that.

What I’ve found happens is that over time the box dye fades on the highlighted hairs which is actually quite a nice look.

Great!! Was the condition ok?

I really wouldn’t do it. I’ve done it before and the dye fades out really unevenly and made my hair look terrible!

Did you use a permanent dye?
Argh I don't want her to balls it up

I use box dyes on my highlights during lockdown and yes the dye fades and then you are left with a nice look. I use a permanent dye and that seems fine.