Mike:

Do you mean that you want to be able to edit the 'Actual Ship Date' on an invoice? The actual ship date does default to the login date. For my clients who analysis the actual vs expected ship dates having the expected date change during invoicing would not be a good thing.

What is the business purpose of having the expected ship date change to the log in date during invoicing? Maybe there is another way.

Correctly editing either date with GV RW would not be a problem. Incorrectly editing anything with GV RW could have serious consequences.