Add Parts to Existing EC
Add Parts to Existing ECTo add parts in the context of a particular EC, see Attach Parts to EC.
You may also add parts and specifications to existing ECs:
from a Part | from an EBOM | from Part Where Used | Create EC on Part Workbench | from Tab Drawing Parts or Specifications | with Multiple Parts in a Project | with Multiple Parts Across Multiple Projects -- My Engineering View > Parts Page | with Multiple Parts Across Multiple Projects -- Collections
To add to an existing EC, follow the instructions in the link, above, to "Create EC" from that location, except:
Instead of 
or 
, select the 
or 
button.
A Search window to locate and select the EC displays.
Search for and select the EC.
Click Submit.
Be sure to check the Requested Change field to ensure the default value matches the required change for the parts and specifications in your EC.