Maintaining detailed invoices in both accounting systems may seem harmless, but it is highly undesirable and prohibited because it would introduce overlapping functions, data synchronization issues, and accounting problems.    

Sales orders are handled by DBA because order entry, picking, and shipping are intimately associated with MRP and inventory.  Invoices are generated from shipments and are the basis for a variety of sales data views and reports.  

Accounts receivable is a financial accounting system function.  For the purpose of tracking and collecting monies owed and paid by customers, only invoice total amounts are relevant, which is why a one-line voucher style invoice gets transferred.  

It is not harmless to replicate the DBA invoice in your financial accounting system.  All the line item detail -- meaning items, descriptions, quantities, notes, prices, discounts, costs, tax codes, tax amounts, sales accounts, COGS accounts, lot numbers, and serial numbers – would require supporting tables and values that would have to be synchronized with corresponding tables and values in DBA.  

Invoice line detail would create duplicate GL postings.  Each line must post to its own sales account, COGS account, and tax account.  These postings have already occurred in DBA. 

In order to include inventory items on invoices, inventory transactions are needed, which would require inventory transfers from DBA that introduce a host of issues maintaining inventory in two systems.  

Duplicate invoices would also mean that an invoice is capable of being reversed and edited in either accounting system.  Each such reversal would have to be reflected in the other side to keep invoices properly synchronized.  

The integrity of the two accounting system design absolutely depends on the complete avoidance of duplicate functionality and data synchronization.  Therefore, invoice detail is confined to the manufacturing system  

WARNING: Be wary of any consultant who proposes to re-create detailed invoices in your accounting system.  This indicates a fundamental misunderstanding of the financial transfer process or a lack of scruples in charging for a completely unnecessary feature that is inherently problematic and not in your best interest.