Advice Needed for Implementing Clearing Logic for Collective Bills

[former_member662169]

We are implementing clearing for collective bills in our PSCD FI-CA system.

Reading through SAP Collective Bill Cookbook and Google searches, I understand that clearing of collective bills is comprise of 2 steps:
1. Assignment of the clearing amount to the statistical collective bill item, and
2. Split of the clearing amount of the statistical collective bill item determined in the first step over the related individual documents.

SAP provides standard clearing variant 20S for clearing Collective Bills. The standard clearing variant only has one step that sorts by Due Date i.e. characteristic 010.
However this clearing variant is too basic to meet the desired clearing functionality of collective bills -- "A clearing variant defined for clearing type 20s must ensure that the clearing amount due for the collective bill is distributed completely to the related document line items."

Looking for advice from others on the clearing steps for CLR variants used for collective bills.