You have to do Enter Finished Production to get the parts into stock so they can be issued to the next level work order.  You could use the IS Tech Batch Finished Production to process a group of work orders and if the WO Default is set to close the WO at Enter FP, then they will also be closed.  How are you issuing the materials to the work orders?  That is another step you need to do to have everything flow correctly.  If you have a lot of components and subassemblies, then backflushing and Batch FP is probably the best approach.

It is part of the standard IS Tech updates you can get for $35/month.  
 
It simply allows you to enter a list of work order numbers and completed quantities and then click process and it does the Enter Finished Production and if the quantity complete equals or exceeds the Work Order quantity and your defaults are set to close WO in Enter FP, it also closes the work order.

The program could be modified to do that but that is not the way it currently works.  If you are either collecting labor through Data Collection or entering time sheets in WO-M then it would be a change to the labor posting program but there are a "ripple effects" to consider.
 
In its simplest form, when posting labor, if an operation is the last operation on a Work Order routing, automatically enter finished production for that quantity.  Once the quantity complete for that last operation meets or exceeds the work order quantity, close the work order.
 
However, the batch of labor entries being posted or the open/unposted labor file may also include entries for the same work order but an earlier operation - you can't close the work order until all labor is posted nor will the Enter Finished Production costing be accurate if prior operation labor hasn't been posted.