Suggestion IP.Nexus: More flexibility for upgrades

There are cases when upgrades in a group of products are offered only for certain products within the group and the upgrade price does not always equals the price difference between the 2 products.

Example:

Package A: 35$
Package B: 50$

Package C: 75$
Package D: 100$

Say I only want to offer the following upgrade options at the specified prices.

A -> B : $20

A -> C : $45

B -> C : $30

B -> D : $55

C -> D : $30

I was thinking of something like the renewals where we can add different renewal options except now it would be multiple upgrade options. For each one, we would select a package that can be upgraded from and enter the upgrade price.