I'm a little bit confused as to what you mean. From experience you cant get a nice clean blonde from just doing a colour cleanse from a xxl home kit. ESP red! Next to black it's the hardest colour to remove. I'd rather foil coz at least that way it conducts the heat better and you'd be able to get a nice light blonde.
- I'd colour cleanse the red tone out
- foil with as many highlights as the client desires
- use a ash based quasi to the remaining hair
- allow to process and tone as nescessary.
Id use highlights as I think it's a nicer way to build up the blonde. At least that way you can add to it and personalise it with what works for the client. So yes, you can add more if you want to.. It's just a case of weaving out more of the darker blond base and lightening that. If she's happy with the amount of blond then just do the roots and possibly add a few lowlights.
Also the breaks in between having the highlights allows for the hairs lipids to restore, thus, preventing damage by doing it all in one go.
There's a vast array of aftercare for all different types of hair needs. I guarentee you'll find one for highlightened hair that has also been stripped.
As I said that's just how I would do it