What does it mean to call bone fortune-telling a substitute for osmanthus fragrans?

How to explain the sentence "substitute osmanthus with flowers"

This sentence means * * using skills, means or methods to transfer the advantages or characteristics of one thing to another, so that the latter also has the same advantages or characteristics.

The allusion of this idiom comes from an old legend. A maid-in-waiting stole osmanthus branches from the palace and tried to plant them in her own yard, but failed. So she grafted osmanthus branches to a plum tree at home, and the plum tree also gave off the fragrance of osmanthus. This allusion tells us that as long as we do it with our heart and replace trees with flowers, we can make our life better.