Best Practice for Discount Schedules for New Sales and Amendments

Hello, 

I am trying to understand best practice for discount schedules when applying to a brand new sale and when applying to an amendment. Here are the scenarios:

1. New Sale - pulls in current discount schedule. The discount schedule is using either the SBQQ__Quantity__c field or a custom quantity field. Cross Orders is checked true. Some discount schedules have aggregation scope blank and some have aggregation scope set to Product.
2. Amendments - subscriptions lines being pulled in through the amendment process apply the original discount schedule as expected. Any new lines added are applying old discount schedules without a tier. But we want the new discount schedule to apply to new lines. Things to note are in number 1 above the SBQQ__QuoteLineQuantityField__c and the fact that Cross Order is checked as true. I have written a price rule that does the following and is working as expected on the new lines but I am not getting the Discount Tiers. Do I need an additional price rule to apply the tier or do I need to create duplicate Discount Schedules that look at the SBQQ__EffectiveQuantity__c field for amendments?
   1. Price Rule Header
      1. Evaluation Scope: Calculator
      2. Lookup Object: SBQQ__DiscountSchedule__c
      3. Calculator Evaluation Event: Before Calculate
   2. Price Conditions
      1. SBQQ__Existing__c equals false
      2. SBQQ__Product__c not equal to blank
   3. Lookup Query
      1. Query 1
         1. Tested Object: Quote Line
         2. Match Type: Field Value
         3. Tested Field: SBQQ__Product__c
         4. Operator: equals
         5. Lookup Field: SBQQ__Product__c
      2. Query 2
         1. Tested Object: Quote
         2. Match Type: Field Value
         3. Tested Field: SBQQ__PricebookId__c
         4. Operator: equals
         5. Lookup Field: SBQQ__Pricebook__c
      3.   Query 3
         1. Match Type: Static Value
         2. Tested Value: true
         3. Operator: equals
         4. Lookup Field: Active_for_New_Quote_Lines__c
      4.  Query 4
         1. Match Type: Static Value
         2. Tested Value: 2026
         3. Operator: equals
         4. Lookup Field: APricing_Year__c
   4.  Price Actions
      1. Price Action 1
         1. Target Object: Quote Line
         2. Target Field: SBQQ__DiscountSchedule__c
      2. Price Action 2
         1. Target Object: Quote Line
         2. Target Field: SBQQ__DiscountSchedule__c
         3. Source Lookup Field: Id

Thank you.