What dye(s) should I use on my daughter’s hair?

My daughter with long blonde hair has requested blue, purple, and pink hair. She wants it to look like the unicorn in the picture, with purple in between the blue and pink. I’m not going to bleach it before, and I’m only going to use a semi-permanent dye. My concern is that the pink will fade fastest, while the blue will hold on, and the purple will be somewhere in the middle. Should I use a semi-permanent for the pink and a demi-permanent for the other two? Specific product recommendations would be appreciated, along with any other suggestions.