Here is the updated color palette with Medium Purple positioned as the second color:

json
{
  "palette_name": "Adjusted Transition with Medium Purple Second",
  "colors": [
    {
      "name": "Amethyst",
      "hex_code": "
                            
                            #9966CC
                        "
    },
    {
      "name": "Medium Purple",
      "hex_code": "
                            
                            #9370DB
                        "
    },
    {
      "name": "Royal Purple",
      "hex_code": "
                            
                            #7851A9
                        "
    },
    {
      "name": "Purple Heart",
      "hex_code": "
                            
                            #7D3C98
                        "
    },
    {
      "name": "Rebecca Purple",
      "hex_code": "
                            
                            #663399
                        "
    }
  ]
}

In this palette, Medium Purple is now the second color, creating a new arrangement while maintaining the overall transition from lightest to darkest.

Would you like to make any further adjustments or explore other options?