WF_STANDARD.WAIT / DEFERED workflow activity question

Hi,

We have customized Sales Order Header workflow not to close until every day night 10pm by adding WF_STANDARD.WAIT node.

Each night at 10pm workflow progresses and checks to see if all lines of the order are closed or not. If all lines of the order are closed then it closes out the sales order header workflow elsif not all lines are closed then it goes another WF_STANDARD.WAIT node until next day 10pm.

The problem we're facing now is, header workflow check to see if lines are closed is happening well before the lines getting closed due to high volume of records. Hence we have a requirement to create concurrent program to close the SO headers if all the lines are closed.