Three way Transaction Matching balance report for two data sources only

Summary:

We want to get a balance report that includes only one source system and one sub system

Content (required):

We want to match Data Source A with Data Source B, but we need a third system C between them to achieve a three-way matching. So we load the third system twice and Sub C is matched with the Source A and the Source C is matched with Sub B. Therefore, if there are any unmatched/supported/in transit, they will appear twice in both the source and the sub system.

In the Balance report, we want to show the unmatched/supported/in transit transactions for Source A and Sub B only. Is there a way that we can apply a filter on the balance report?