It is possible to achieve this requirement using the import events introduced in Tally.ERP 9 Series A Release 3.0. For example, you can synchronise purchase voucher and at the other end, it will be imported as sales voucher.
The eventsStart Import, Import Object and End Import, gives the complete control to the programmers to manipulate the data prior to importing the same into the company. Please refer to the TDL Reference Manual for detailed explanation.
