Complictaed pricing scenario

Hi

I have a scenario in my project with regards to pricing

The pricing for the client is as follows

There are four condition types

ZCON1--Basic price

ZCON2-Premium

ZCON3-Discount 1

ZCON4-Discount 2

Based on the these foutr values a fifth condition type ZCON5 has to be determined

I tried keeping condition records for first 4 condition types and tries to determine value for ZCON5 using From and To fields

But the value for ZCON5 has not been determined by this technique

Is it possible to determine value of condition type using From and To fields or is it necessary to using Alternate Calculation type field and use ABAP routine

Kindly guide me on this matter

Thanks and Regards

Sunil