In current behaviour, marked transactions by one user in Ledger Settlement will be included in settlement by any other user who firstly clicks on Settle marked transactions button. 

As reported several times in issues, especially in issue 636711 Marked transactions by one user in Ledger Settlement showing as marked for all other users : Ledger Settlements and a different user enters the ledger settlements module, they have the same transactions pre-marked and amount generated in the Marked field. 

With an improvement, the expected behaviour would be to settle only marked transactions by the user who clicks on Settled marked transactions. This improvement seems to be able to be done since marked transactions are currently flagged with userid in table LedgerTransSettlementWork.

This behaviour would allow to let each user work on settlement without being interrupted by another user, since with a large number of transactions the marking step of settlement can be time consuming and could require to be done over several days.

This improvement would avoir error on settlement.