The message you received in regards to posting journals includes not ony those for invoices, manual checks and adjustments, but also system checks and reconciliation. You need to print and clear the Check Register and the Check Reconcilation posting journal in order to gain editing access to the Control Account Set records.

There is no good reason why the software won't allow a user to do xwisten wants to do, as long as there are no open batches. This limitation is there simply because "that's the way it's always been done".

Please consider relaxing this limitation in the next release of AP.