Setup inter-company in QuickBooks Online (QBO)
Although you can create multiple receivable accounts in QuickBooks Online Singapore version, the receivable field is not available in the sales invoice form. The intention ‘could be’ trying to simplify the process by having one receivable for each currency to prevent a mistake in the classification of account. For those who are using multiple receivable accounts in QuickBooks Desktop may take note of the differences.
Some user may create the subsidiary as a customer or supplier in QuickBooks. You can print a standard Profit & Loss or Balance Sheet report and set the column to display either by customer or supplier. You do not require any additional setting but have to separate the customer and supplier into two difference report. It’s workable but maybe a little tedious to some accountants.
How about using the class feature?
QuickBooks Online manages the class slightly different from the Desktop version. The class selection is only available for the detail line of the transaction, but not for the transaction header account such as a bank, receivable or payable. For example, you can select a class for the expense account but not the payable when entering a bill. You can have a Profit & Loss with the column by the class report, but not an accurate Balance Sheet by Class.
Consider location instead.
QuickBooks introduces the location feature in the Online version to categorise the data from multiple warehouses, branches, or inter-companies. The usage is similar to the class feature, but it affects both header and detail line accounts when a location has tagged. You can prepare column by location for both Profit & Loss and Balance Sheet, which helps the accountant prepare contra during consolidation.
Location on Bills 
Balance Sheet by Location 
Location on QBO invoice 
Profit & Loss by Location
Try location feature if you haven’t done so. Let us know how you managing inter-company billing in QuickBooks Online 🙂