Need formulas for client fix today!

Short background: Asian client with course hair, a lot of hair, pastor shoulders. Box home coloring for 10 plus years medium brown. Her desire was to have her color evened out and dimension put in..

The problem: She has a lot of gray and silver blended through her charcoal brown hair. She did not to color all of her hair, she just colored parts of her hair in a very uneven way over 10 years. I'm sure you get the vision. (She was also quite clear that she was not going to come back in 6 weeks for a touch up that she was going to go back to her box color. So could I please not Make it look too "colored")

I applied Schwarzkopf 7:00 nn with a quarter of 8:00nn & 20v and process the hair.

I did a root touch up on the crown and pulled the color through in a feathering way so that it would not be solid throughout the crown. Below the crown and in back. I just colored it all. Because it was a nightmare. Highlight test with lifter & 20v predictably did nothing Was also testing lifter plus 30 v.... That works somewhat. She's coming back today to have me put in proper highlights because it didn't lift much. But she doesn't want to have screaming blonde highlights.

I know this is a very long Story. I really do need your help ! What formulas would you use to give her noticeable highlights that aren't super blonde.? This is for a family wedding and she really needs it to be perfect. ❤️🙏🙏🙏