Addition to default Debtor / Creditor control Nominal Account, some customers have asked to allow them to assign a separate NL Control Account at Supplier / Customer account level. By default Customer/Purchase Account will have default debtor/creditor Nominal Codes assigned. But if customer choose to create a separate NL code based on Trade Type with Sup/Cust then they want this flexibility to assign a separate NL code to customer / sup account level as NL control account.
With the additional Nominal accounts for the sales/purchase ledger, you could also create dedicate nominal control account per currency and when you do a foreign exchange revaluation at the end of the month, you know the which ledger account have been impact by this. Current the single nominal ledger has tens of thousands of transactions is a single month and splitting it would make it easy. Right now I am spending to much time data dumping and reconciling multiple ledger reports to balance back the nominal account to the TB closing balances.
True, the CC/Dept will also be used for the VAT control accounts. That may actually be useful to enable reporting on VAT by trade type. If not, the VAT transactions table (SYSTaxTran) does not have the CC/Dept
Making the above change noted by Geoff would impact other accounts not just the debtor and creditors control.
If the "Trade Types" in the suggestion can be set as cost centres, then this can already be done using the "Split postings between cost centres..." option in system settings, and setting "Use Specified" to No for the control accounts in NL Default Accounts.
See https://desktophelp.sage.co.uk/sage200/professional/Content/NL/MaintainDefaultNominalAccounts.htm