Rollover / Order dilemma

We are new to Tessitura and just processed our first rollover.  The rollover process worked fine but due to some challenges with the old source data we have a problem and I could not find help in the posts.

We need to cancel part of an order that was created as part of the rollover process.  I could use my "SQL sledgehammer" to correct this, but I'm certain a more appropriate process exists. 

One of our patrons was essentially double-billed for a package.  The patron has two identical packages and each package has seats in different sections (again, the source data contributed to the problem).  Only one set of seats is valid; the seats in the other package should be deleted.

I attempted to delete the seats from the Sub Line Items tab.  This message appeared:
Package sublineitems cannot be deleted.   Entire packages can be deleted from the Lineitem view
Or .. if I select multiple seats, this message: 
One or more of the rows selected is for a locked performance and cannot be deleted.

From the Line Items tab, I attempted to delete the package with the "bad" seats.  This message appeared:
One or more of the rows selected is for a locked performance and cannot be deleted.
I also tried to delete the seats from the Line Items tab.  Not surprisingly, that didn't work.

If the seats are returned using the seat map, this message:  The seat cannot be returned.

I tried the change process (which uses the Upgrade button)m but that didn't resolve the problem.
I even tried the "unseatable" button.

Fortunately, this trial & error method was in our Test system.

The rollover process generated correct orders for almost all of the existing subscriptions (again, from our legacy system).  The process only affected a few.

Our season launch event is this week and we will need to ability to make corrections to orders.
Not only cancel parts of orders but make changes to orders.

Hoping someone can help?

Thank You  very much
Wendell Baskin
Bass Hall - Fort Worth
wbaskin@basshall.com