Suggestions:
Yes, System has the facility to add multiple vouchers with different sundry codes in the details screen of payment against voucher. If users have to add multiple vouchers when adding multiple line items then sundry code in the header screen should be left blank. Payment type can be selected as cash or bank.
If processed for a single sundry then sundry code needs to be set in the header. irrespective of payment mode. Single payment entry against multiple sundry’s is required when bank pays to multiple parties against single reference number given by the customer.