After supporting references balances setup component is tagged to subledger journal entries, what type of reports need to be created so that the information is available to users?

A customer's business requirement demands a more granular view of transferred subledger journal entries in GL.
Which of the available General Ledger Journal Entry Summarization options meets this requirement?

The new billing source system has been registered into Accounting Hub Cloud. The subledger is in active state. At a later date, the business decides to bring in another legacy system (for example, a payment system) for accounting in Accounting Hub.
What two options do you have?

What is the key attribute that is used to query journal entries of a registered source system?

You are implementing Fusion Accounting Hub for your external Accounts Receivables system. The external system sends invoices billed and cash receipts in a flat file, along with the customer classification information.
You want the accounting amounts to be tracked by customers too but you do not want to add a Customer segment to your chart of accounts.
What is the solution?