Yes, I found this information as well. Unfortunately I could never figure out the riddle to answer the questions in a manner to be able to get to the option to pick only the state return. Every option I chose forced me through the federal menus. As my tax credit is state specific and affects nothing federally I don't want or need to amend or otherwise touch anything related to federal but I can't get "the technology" to cooperate.
Then just complete the federal amended return without changing anything. The program will take you to the state return so that you can amend the state.
In the File section of the program when you are finished you can designate which tax return needs to be filed.