It seems well-established that combinations of more than just two dyes are supported:

• Light Grey = Grey + White = (Black + White) + White
• Magenta = Pink + Purple = Pink + (Red + Blue)
• Magenta = Pink + Purple = (Red + White) + (Red + Blue)

Since these are existing recipes:

• Magenta = Pink + Purple = (Red + White) + (Red + Blue)
• Purple = Red + Blue

The recipe for Magenta = (Red + White) + Purple can be considered missing.