Rate fact group link to rate category scenario

[Former Member]

Need suggestion on below scenario

There are 20 customers and there are close to 12 price keys and there is a price change for the 18 customers begin increased but for 2 customers who are using 4 price keys out of the 12 the price change is not implacable and remains the same . The billing engine rates and calculation are common to all the 20 customer and no change in rates applicable but only price is segregating the two sets of two customer and 2 customers using the same rate category these two customers are basically opt out of the price change

so new rate category needs to be defined segregate the two new customers and 18 customers to be used in installations of these 2 customers , the calculation and schema logic is same for both sets of customers what is the best solution to with minimum effort and time need to brainstorm, the prices are maintained in the rate facts of rate for all customers and some price keys remains same and rest are increased.

option 1

1) Define a new rate category and copy existing rate to new rates and new schema and change the price keys in the the rate facts as applicable

2) Create a fact group withing the existing rate and change the price key there

( but how to link the new fact group with the new rate category as the fact group is in the rate facts and it is linked to old rate category and how the new fact group will be linked to the new Rate category if this is the easiest approach

3) the fact maintenance hierarchy I cannot change since it will affect the old 18 customers

4) giving credit and manual bill is temp solution we need to put changes in configurations

what is the best approach to do this , fact group i sthe easist solution but i am not sure how it can be linked to the new rate category so that i takes up the price for 2 customers