If you choose to file a joint return for Nebraska, you will have to both be treated as residents and report all income. You can choose to file a separate Nebraska return, but you will have to create a "mock" federal return. You would need to do this same with a separate New York return.
See How do I prepare a joint federal return and separate state.
No. You can create separate online accounts. It is quicker and cheaper to use the desktop but not required.
The desktop version allows you to start with the basic information and save it. Add or subtract and save with an new name. Add or subtract more, save with another name. You can have many files on the desktop version.
We already filed jointly using my account for federal. Would it be possible for her to use her account to file her state part ? I know I can efile my state tax now since it's my account used but would she be able to use her account for that? or do you mean we restart the federal from her account and then we don't do the efile for her just print and mail and discard the federal ?
Yes, you can do a separate TurboTax account to create the mock return, you will have to print and mail since you will not be filing the federal return. @ali-aldamen