Several airlines do allow changes in passenger details, even after issuing a ticket. At the moment, changes are allowed by BA, IB, AF and KLM airlines. What can be currently changed:
AFKL: Modify names, surnames and title. Add/modify documents.
BA: Modify names, surnames and title (surname only on the on hold orders). Add/modify documents.
IB: Modify names, surnames and title.
Where to do changes
You can change details for both on hold and ticketed orders. Go to the order, click on Order Details and scroll down to passenger details. You will see a red button 'Change passenger data' which will allow you to proceed with changes.