Sorry,,,can't be done that way. Your computer already has had it's free state. Buying or installing another desktop copy does not add a new free state.
Either Buy the extra state...or install her desktop software on a different computer that hasn't had any 2018 TTX software installed on it yet....and see what happens there. There may be some hacks that will allow it, but you risk losing access to your own tax files.
_____________________
You could try Customer Support and see if they will do something, but they are pretty hammered for the next few days.
https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*