You can use the adhoc Sundry change option to achieve this by following the velow staps.
This is in the 3PL tab at the top of Delta.
Select Add Sundry Charges.
Select the Account from the Account drop down box.
Set the Charge Date.
Press the + button to add an Adhoc Sundry charge line
Enter in a Sundry Code, Description Quantity, Price.
The Total will auto populate.
Enter in a Nominal Code if needed
Select the VAT Code.
Press OK to save.
What this will do is when the charges are generated for that date, this will add on this adhoc Sundry charge for that account.