Maintaining shadow roots? Silver and grey

[HugAMale]

Hiya,

I'm about to use Schwarzkopf siverwhite silver on lengths with the slate grey blended on the roots. the hair has already been lightened all over using blondor multi blond, 20vol and olaplex (2 processes on roots, 3 on lengths) currently it's in fairly good condition but I'm concerned what will happen in several months time when the roots have grown past the desired point and need lightening back up to the silver. Is there a way of removing the slate grey that won't involve bleaching again? The roots are already a level 9 so I'm concerned about breakage if it's bleached again in the future.
I realise I needn't of lightened the roots so much but smokey roots was an afterthought. I think it would be a good idea though as the hair is naturally a level 4 so regrowth is going to be pretty blunt.

There seems to be a lot of info on how to achieve the smokey roots but little on how to maintain it. Any suggestions welcome.

Thanks for reading

 

[JJH93]

I usually find by the time my clients have come back in the grey at the roots has faded out to a silver or white anyway so I just proceed as if I'm starting from scratch but I use dove grey at the roots and silver on the ends