For release S4 FINANCE more flexibility was introduced regarding currency configuration. The Universal Journal in SAP S/4HANA can handle up to 10 currency fields.
It is possible to have 2 fix (Local and Global currencies) plus 8 freely defined currencies for GL (3 for AA, 3 for ML, and 2 for CO). The 8 freely currencies can be defined on ledger level.
However, the currencies for parallel ledgers do not depend on leading ledger.