On the multi-company voucher screen, there is a field called Group ID. As the error message says, there should be only 1 posting in the session company per group ID (1, 2, 3, etc.).

To have multiple rows of postings for the session company, add them with different group IDs. 

Hi Leave,

Thanks for the response,

but when I add 1 posting line for the company I get the below error,

Here my reequipment is that to add  one set of debit credit transactions to one company and another set of debit credit transactions to the other company.

Please call me Ieva. 

In the header, there is a field “Manual Balance per Company”. If this is not selected, then you do not have to manually add the balancing line per each company - the balancing entries are done automatically according to posting controls AP10 and AP11.

The idea is that there is a single posting in the session company with Group 1 with opposite side postings in the other companies with the same group ID 1. So each group balances to zero, but the balancing entries are handled automatically. 

This is from IFS Help files and might be helpful in explaining further: 

If Manual Balance per Company option is enabled, the voucher rows per company must balance in accounting and (if used) parallel currency before the voucher can be saved. If aforementioned option is disabled, any remaining balance per company will automatically be posted using the posting types AP10 (credit balance) or AP11 (debit balance). Also, the voucher rows within each Row Group ID must be in the same transaction currency and must balance in that currency. Only one voucher row is allowed for the source company within each Row Group ID.

If the Voucher Row Group Validation option is enabled in the Voucher Type page for the used voucher type, voucher rows with the same row group ID must have a one-to-one or one-to-many debit/credit relation. In order to save a voucher of a voucher type for which the Voucher Row Group Validation is enabled, the debit balance and the credit balance must be the same within each row group ID.