How to deal with historic override rate in multi currency app

Summary

Historic override rate is taken into account on base level but not on parent / sub consolidation level

Content

Dear all
I would appreciate some advice on historic override rates. These have been applied to base level entities entity currency against USD as the overall default reporting currency is USD. However, these override rates are not taken into account on sub consolidation level. Support tells me FCC is working as per design but not giving a solution how to fix this.
Base entities are AUD,
first level subconsolidation parent currency is AUD but when retrieving data in USD reporting override rate is not taken into account. Any idea on how to do this so that it roles up properly to the required parents in sub consolidation?