Have one reporting currency to one ledger set

Summary:

I would like to use one same reporting currency to several ledgers, and prefer to group all the ledgers I need to one ledger set so that I can run reports in one time.

Content (required):

So far I've tried followings but all get stuck.

1. Use same reporting currency name under different ledgers, but this is not allowed in Oracle.
2. Setup ledger set to gather all reporting currency under different ledgers, but it looks like reporting currency cannot be added in the ledger set.

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