Multiple people can file with the TT desktop, including their state returns. The "One State" that you see mentioned frequently in the store-bought version refers to the fact that software for one state (eg CA or NY or AZ...) is included in the original purchase price. If one of the filers using your package has to file in a different state than you, you must download the additional state software for $39.99. There is also a filing fee for each state you efile with.
Note that there is no limit to the number of returns you can prepare on TT, but you can only efile 5. You would need to prepare the extra returns, print them out, and send them in via snail mail or the like.
