How to setup usage pricing to bill usage for a location based on consolidated volume across location

Need to bill usage line based on the rate for consolidated volume across locations. Usage will be of type Actual per period.

Location 1 : C1 ( Counter 1)

Location 2 : C2 ( Counter 2)

Location 3 : C3 ( Counter 3)

Pricing bands :

1  - 500 : $1

501 - 1000 : $2

Usage contract will have 3 usage lines, one for each location/site. Each usage line will have one subline.

Location 1 usage value should be billed at per txn rate of $1 if total counter value across locations ( i.e C1+C2+C3  ) is less than 500. Else if > 500 then the rate should be $2 per txn.

As an example , if C1 = 100, C2=300, C3=200 then subline for location 1 should be billed as C1* $2 = 100*$2 = $200.Location 2 should be billed as $600 ( 300*$2), location 3 should be billed as $400 ( 200*$2 )