Hair help- straight process

I had JHS over a year ago. I want to color my hair and do keratin from now on. Just wondering if I can do highlights over the old JHS and eventually do the keratin treatment. Or do I need to stick with doing the single process color. Can they do keratin over the old JHS?

Thank you

Hair help- straight process

You need them to do a strand test., I had this issue. Did JHS and 2 keritans didn't take...went to someone in greenlawn that specialized in this. been 2 years and salons still nervous about highlights. Did a strand test a few weeks ago . it was fine but hair can break after JHS if you highlight. still not sure if I will do highlights. I do just keritan now.