Expense Approval - Dynamic cost center custom role derivation

Summary:

We have a requirement to route the expense approval to set of users based on cost center and different amount ranges.
In order to achieve this, we created custom application role for each cost center matching the role code to cost center value. Rule is written in BPM using resource list builder and provided cost center attribute "Expense Distribution.Cost Center" in the application role attribute. This rule worked dynamically deriving the default cost center and assigned to users based on the role code matching the cost center.

Issue is with the amount ranges along with the cost center when the role is created. For example, there could be amount ranges of 10000 gbp and 20000 gbp for the cost center 1000. How do we derive the cost center dynamically along with the amount range something like 1000_10k, 1000_20k?